Disclaimer: Opinions are mine.

Satellite imagery between 2012 and 2015 had led to the exposé of widespread dredging of fossilised giant clam shells in the South China Sea. The distinct arc shapes, visible from space, were the result of boats chopping along the reefs. What was even more surprising is that this was done to reveal the buried giant clam shells!


My curiosity brought me to Tanmen Village, and I shared my story through a photo-essay earlier this month, and published it here. Now that you have seen the industry through my eyes, I wanted to provide the contextual insights of the Chinese cultural history, industry and how businesses have bloomed since the introduction of giant clam shells as materials.

Advisory: This is a 15 min read.

1. Significance of Giant Clams (硨磲贝) in Chinese’s cultures

Culture or ‘the way of life’ usually plays a big role in influencing people’s habits and mindsets. Whether they are a fisherman, a craftsman, a farmer, or a religious priest, their actions are mostly driven by their cultural beliefs and hand-me-down stories. It was a similar situation for the giant clams and the Chinese’s lifestyle.

During my walkabouts in Tanmen Village, I’ve learnt several interesting details on what the Chinese thought of the giant clams:

  • Giant clams are one of  China’s treasures
  • Considered a rare organic gem (有机宝石) that is produced by animals – the purest of white ‘jade’
  • At times, they are referred to as the ‘jades of the sea’
  • Has been mentioned as one of the seven treasures in Buddhism
  • Believed that it can help ward off evil and protect the health of families based on its supposed healing properties
  • People are aware that giant clams are nationally protected species (国家一级保护动物), thus making them even more highly valuable!

Okay, so my initial conclusion was that this appears to be one of the typical beliefs that the animals had special properties to aid with health issues (something like the rhino’s horn, tiger’s penises, and seahorses). And the other facts were to stimulate the demands and sale of giant clams in China – a marketing strategy.

Or so, I thought! Later in my exploration of the shops, I found this book entitled “National Treasures – Giant Clams” by Li Heng, a Hainanese-based writer whose interests is to promote the cultural heritage of Hainan Island. On the front cover, it also says that this book is the first of its kind to discuss extensively on giant clams in China.

THIS WAS A TREASURE FOR ME! Imagine my excitement when I ‘accidentally’ came across this book! I was glad that I’ve left no stones unturned, and what I read what absolutely compelling. 😀


It seems like the giant clams go wayyyyyyy back in Ancient China (most conclusively present in the Qing Dynasty)! As a child, I loved watching the ancient Chinese dramas, where the court officials have their ‘furry hats’ on, beaded necklaces, and embellished overalls. NOW I know that the beaded ornaments were made from giant clam shells! It was also mentioned that because gold was common in ancient times, the giant clam shells cost a lot more than gold!

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2. Valuing Giant Clams

Shells from Scarborough Shoal were considered of highest grade

I was told by the shops that their shells came from three areas in the South China Sea, and the quality of shells decreases in the following order:

  • The Scarborough Shoal (黄岩岛): Considered the best shell grade because they are uniquely colourful (red, purple, brown, yellow, green, white), and their shells are dense and least brittle. Due to the rarity of shells from the geographic locality, they are highly prized.
  • Spratlys (南沙群岛): Ranks behind those found at Scarborough Shoal, but comes in fewer colours (mainly yellow, brown, white), moderately dense but brittle. Most carving products in the market are made from shells in the Spratlys.
  • Paracels (西沙群岛): The least favoured but abundance of materials. Few colours (mainly yellow, white), and tends to be most brittle of the three. Not suitable for large carvings, and generally mass produced as white beads.

Pricing the products based on colours, translucency, and perfect cuts

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Table 1. Shell handicrafts were generally priced based on the rarity of colours, translucency, and lack of defects/cracks.

While the origins of shells matters to the craftsman (as it determines the type of handicrafts produced), the products across the various shops were priced quite similarly based on Table 1. For instance, the costs for the same 108-Buddhist beads made with the colourful Scarborough Shoal shells versus the plain-looking Spratlys shells could differ by 50 times (in the Chinese currency, Renminbi)!

Tanmen - 7Tanmen - 6

Giant clam-shell based products are hard to counterfeit

To understand why the locals treasured handicrafts made from giant clam shells, I found myself relating my observations to the biophysical properties of giant clam shells. Here are some reasons:

  • Good quality shells are hard to come by, and in this case, those found at Scarborough Shoal.
  • Every product made from the giant clam shells are unique and one of its kind.
  • They are difficult to counterfeit.

As a young tiny larvae, giant clams are builders. They build their own shells by making aragonite – an alternate form of calcium carbonate. This shell-making process may be affected by the reef environment they live in, for example, the availability of light, nitrogen, or carbon can determine how well they build their shells. To add on, each giant clam is distinctive with their own pace of constructing shells – some individuals may grow very fast, making thinner but bigger shells, while others grow slower, making thicker but smaller shells. Lastly, similar to tree rings, the shell growth pattern of giant clams resemble ‘rings’ – representing days, weeks, or years!

Watanabe et al., 2004
Figure from Watanabe et al. (2004) Palaeo 212: 343-354. (a) Tridacna gigas shell from Kume Island, Japan. (b) Optical transmitted-light photograph of the inner shell layer of T. gigas. Dashed lines represents sampling transect for isotopic measurements.

3. Businesses As Usual? (accurate as of 11-12 August 2016)

After my ground surveys, I mapped out my thoughts and this Figure 1 summarises the simplified version of the various businesses.

Tanmen 1
Figure 1. Mapping out the connections and activities of the giant clam shell business in Tanmen Village.

Business Players Big and Small

The major business players are those with processing factories and warehouses. When I spoke with the owners of these businesses, I found that they have been selling giant clam handicrafts for >10 years, and bought their shells from specialised giant clam fishing boats. By late 2016, where many clam fishing boats have ceased activities, one of the owner boasted to me that they have enough stocks of shells to last them another 10 years of business. She didn’t mention whether their warehouses were nearby, but I believed her words based on what I saw…

The small-time businesses, on the other hand, are not coping too well with their sales. They tend to buy the handicrafts from wholesale, but one man said that business was poor and prices were lower. He has tried his hand to sell online, but hard to compete with the cheaper fakes. They were also very nervous because authorities were beginning to confiscate the products.

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Humans of Giant Clams

I met an owner, who previously specialised in carving ornamental jade for almost 10 years. As the market for jade products became saturated causing their prices and popularity to drop, he was looking for alternative materials for handicrafts. Then in 2012, he began to use giant clam shells and have not looked back since. Clam shells became increasingly popular among craftsman, and many started to buy large quantities from the clam fishing boats. He even told me that several Singaporeans had visited him to buy his products in bulk! :O

Another person was a master craftsman with >20 years of carving experience. He had started with jade too, but decided to move his family from mainland China to Tanmen Village to start a wholesale business on the giant clam shell handicrafts – seizing onto the golden opportunities. As I browsed his humble workshop, his wife and himself were beaming with pride and excitement at the prospects of this new business. One that brings in more wealth to improve their living standards.

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4. My personal notes

I was sad.

I was sad to see the massive piles of giant clam shells in the backyards of factories, hidden from sight.

I was sad as I realised that giant clams used to be this plentiful in the South China Sea.

I was sad because I felt conflicted between my role to be an objective scientist and to feel emotionally connected with the locals’ livelihoods.

But I was also very glad to have gone through this investigation and seeing the trade unfold.

With such a long traditional history of using giant clam shells as ornaments in China, we risk the loss of an important part of human history. By encouraging the trade, we risk the loss of more giant clams, as well as the destruction of coral reefs in its path. I see the problem, and that is the demand for giant clam shells had led to widespread mining of the seabed for them, and in the process also led to massive destruction of coral reefs.

I don’t think I’ll know where to begin solving this complex problem, and I don’t have any answers for you. Maybe you’re thinking, “After reading your story, and you tell me there’s nothing we can do???” Wait a minute! Give me a chance to leave my alternate ending remarks! 😉

I do know (and hope that you feel the same way) that from experiences like this, I am learning to be more compassionate towards issues that science alone cannot solve the world’s problems. As a close friend told me, “If science had been the solution for all the world’s problems, why are we still having this conversation now?” I just laughed and nodded…