Somewhere on a Kumbalangi village walk your host will stop at a mound of broken white shell beside a scorched patch of ground and explain what it is. Nobody photographs this stop. It is grey, it smells, and there is nothing to look at. It is also the most complete thing on the route — a full industry, from the mud to the finished product, inside about two hundred metres.
It starts with the feet
The animal is the black clam, Villorita cyprinoides — a brackish-water bivalve endemic to India that cannot survive in properly salty sea water and cannot survive in properly fresh water either. It needs exactly the half-and-half conditions that the Kochi backwaters produce, which is why it is here in the quantity it is.
In the deeper parts of the Vembanad system men dive for it in seven to nine feet of water and come up with a hundred and fifty to two hundred kilos in a working day. In the shallow creeks around Kumbalangi it is simpler and stranger: you walk out into knee-deep water and find them with your feet, working your toes through the soft mud until you feel the shell, then reaching down. It is done mostly by women and it looks, from the bank, like people standing about in the water doing nothing at all.
The scale is not small. The black clam accounts for more than seventy per cent of all shellfish taken from Vembanad Lake, and the Kochi backwaters alone yield in the region of twenty-five thousand tonnes a year, worked by something like four thousand people, year-round.
Cooked open on the bank
The clams are brought in and boiled in a pot at the water’s edge, which makes them gape. Meat and shell are then separated over a simple sieve — the meat one way, the shell the other — and from that point they are two entirely different trades with two entirely different customers.
The meat is food, and it stays local. It is sold house to house and in the village market, usually by the women of the collecting households, and it turns up in a Kumbalangi kitchen as a dry roast with coconut and shallots. If you are staying in a homestay, ask for it by name — kakka. It is a cheap dish nobody puts on a tourist menu and it is the most local thing you can eat here.
The shell is industry. It is stockpiled, sold in bulk — often through organised fishermen’s societies rather than by the household — and burnt.
Why the shell is worth anything
Here is the fact that makes the whole thing make sense: Kerala has very little limestone. A state that needs lime for building, and has no rock to burn for it, has to get calcium carbonate from somewhere else — and it is sitting in the mud of its own backwaters, in the form of several thousand tonnes of clam shell a year.
So the shells are fired in a kiln, which drives off carbon dioxide and leaves quicklime. Slaked with water, that becomes the lime that goes into mortar, plaster and whitewash — the whitewash on the walls you have been walking past all morning, quite possibly made from shells taken out of the creek fifty metres away.
- Building lime — mortar, plaster and whitewash, the traditional use and the visible one here.
- Cement and sand-lime bricks.
- Calcium carbide, glass, rayon, paper, sugar refining and distemper.
- Poultry feed — ground shell as a calcium supplement.
- And the meat, separately, sold in the village as food the same day.
That list is the reason a shell mound is worth money and the reason the trade survived when so much else here did not. The clam is one of the few things Kumbalangi produces that has an industrial buyer as well as a household one.
What to ask when you are standing there
Ask who collects and who sells, because they are usually not the same person and the answer is a small map of how money moves in the village. Ask whether the shell goes to a society or a private buyer. Ask whether the beds have moved — they do, and collectors will tell you flatly whether this year has been good or bad, which is a more honest environmental report than anything published.
The pressure on this fishery is real. Salinity in the Kochi backwaters is being pushed around by dredging, barrages, reclamation and effluent, and the black clam is a species with a narrow tolerance sitting in the middle of all of it. Nobody standing in the water needs the research explained to them.
And that is the argument for the least photogenic stop on the walk. The toddy tapper is the moment people remember and the Chinese nets are the picture they take. The shell mound is the one that shows you an entire economy — collection, processing, a local food market, an industrial supply chain and an environmental problem — standing in one place, in the space of a few minutes.
Frequently asked questions
What is the black clam?
Villorita cyprinoides, a bivalve endemic to India that lives only in brackish water — it cannot tolerate full sea water or fully fresh water. The Kochi backwaters suit it exactly, and it makes up more than seventy per cent of the shellfish taken from Vembanad Lake.
How are clams collected in Kumbalangi?
In the shallow creeks, by hand and foot: collectors wade in knee-deep, feel for the shells in the soft mud with their toes and reach down for them. In deeper parts of the Vembanad system it is done by diving in seven to nine feet of water, where a collector may bring up 150–200 kg in a day.
Why are the shells burnt?
To make lime. Kerala has very little limestone, so clam shell is the local source of calcium carbonate. Fired in a kiln it becomes quicklime, which slaked with water gives the lime used in mortar, plaster and the whitewash on village walls.
What else are clam shells used for?
Beyond building lime: cement, sand-lime bricks, calcium carbide, glass, rayon, paper, sugar refining, distemper and ground shell as a calcium supplement in poultry feed. The industrial demand is what gives a shell mound its value.
Can I eat the clams?
Yes — ask for kakka at a Kumbalangi homestay. It is usually served as a dry roast with grated coconut, shallots and curry leaf. The meat is sold within the village on the day it is collected, so it is about as local as food gets here, and it rarely appears on a printed menu.
Is the clam fishery under threat?
It is under pressure. The black clam tolerates only a narrow band of salinity, and salinity in the Kochi backwaters is being altered by dredging, barrages, reclamation and effluent. Collectors will tell you directly whether the beds have shifted and whether the season has been good, which is worth asking.