Editor's Note: China is divided into as many culinary regions as there are different ethnic groups. Its geographical diversity and kaleidoscopic cultural profiles contribute to the unending banquet of flavors.

It used to be a poor man's feast, picking at shellfish that could be easily foraged from mudflats, wetlands or sandy beaches. And no one is better at making use of these cheap treats to make delicious food than Chinese coastal communities.

Clams, cockles, limpets, sand worms, fiddler crabs are all grist to the mill. In fact, many of these off-mainstream seafood have become regional specialties over time.

In Beihai, a coastal city of the Guangxi Zhuang Autonomous region, they harvest sand worms for food and flavoring. These 20-cm long tubular fat pink worms hide in beaches and are dug up by an army of workers every day.

Chilled cooked conch on a hill of shaved ice.

They are transported to market, where vendors turn them inside out to clean them. They are then sold to eager consumers who will eat them in delicious stir-fries or slowly boiled in thick rice congee.

Sand worms, shachong, are also dried. The resulting pencil-straight translucent tubes are not cheap, and they are used to sweeten soups and broths. Another interesting method is to salt-roast the dried worms, turning them into crispy, savory snacks that make excellent beer food.

Another unusual "worm" that is a signature snack is the tusun, or earth asparagus, of Xiamen and Quanzhou in Fujian. Like the Beihai sand worms, it is a relative of both the soft coral and the sea anemone.

Unlike the sand worm, however, it is more gelatinous and is cooked down into a clear jelly and served as a chilled cake with chili sauce and plenty of cilantro.

Nothing is wasted, and the coastal folks use everything at their disposal.

Back in Beihai, tiny fiddler crabs are harvested at night and pounded with salt to make a fermented preserve, to be served with the region's famous white-cooked chicken. That turns an otherwise inedible resource into a treasured delicacy.

Further along the coast, at Chaoshan in Guangdong province, little oysters that colonize rocky outcrops near shore are chipped off fresh every day.

They are washed clean of shell fragments before being used in the most famous street food here - oyster omelets.

The Chaoshan people also like oyster congee, a soupy rice porridge with lots of little oysters added, and seasoned with salty pickled vegetables, pepper and cilantro.

Unlike people in many Western countries, the Chinese prefer their oysters well-cooked, including bigger ones that are now widely farmed from Zhejiang right up to Liaoning.

The most common method is to steam them, with garlic, ginger or scallions. Sometimes, rice or bean vermicelli is placed in the shell to soak up the juices.

In China's southern coastal provinces, you can enjoy all manner of shellfish, including a rather gory-sounding delicacy, the blood cockle or xuehan.

This is a relatively small cockle, compared with the larger "hairy" cockle or maohan found in northern waters. They have a salty liqueur in them that looks like blood, hence the name.

These cockles are found in the delta mudflats where freshwater meets the sea, and they are harvested with rakes that turn them up from their hiding places.

Once the mud is washed off, the grey and white ridged shells are exposed. Sometimes, they are simply blanched with boiling water and then eaten with a garlicky dip of soy and chili.

They can also be shelled, and then fried with thick rice noodles, bean sprouts, Chinese sausages and egg - another popular street food served wherever the Chaoshan emigrant has settled.

The mantis prawn is not a shellfish, although it is just as much a challenge getting past its prickly carapace. It is more shell than meat, but the prawn is very sweet, and in season, the roe runs right through the whole crustacean.

Mantis prawns used to be very affordable, a fishing byproduct sold at farmers' markets to the hoi polloi. With declining marine resources, however, their value has skyrocketed.

They are now served in restaurants, steamed or boiled, but they can also be fried in plenty of garlic, ginger and spring onions as well.

On a recent trip to Tangshan, we were treated to a meal featuring xiao haixian, "little seafood".

Platters of hairy cockles, conch, razor clams, yellow clams and mantis prawns filled the table. There were no lobsters, abalones or other luxury seafood, but we enjoyed the freshness of the shellfish just as much, if not more so.

The cockles were blanched and served with a soy sauce spiked with wasabi. But it was the conch that captured my attention and my taste buds.

They were cooked just right, and then served on a little hill of shaved ice. You used a cocktail stick to skewer the meat through the opening of the mollusk and then gently twisted the flesh out.

Unlike whelks and snails, these conch reproduce by spawning and so have no babies inside their innards, and you don't get that uncomfortable crunch when biting into them.

Razor clams are harvested all over China's coastal regions, and normally range in size from 3 to 6 cm. In Guangzhou's Huangsha wholesale seafood market, restaurant owners and chefs go shopping for extra-large razor clams that are as long as a grown man's palm. These are sold at a hefty premium.

More common are clams the size of a little finger, and they are simply fried with plenty of ginger or scallions, or steamed with a blanket of garlic.

The shells are very thin and easily chipped, but the flesh inside is almost sugar sweet, and tender.

Clam varieties are myriad, ranging from large plump yellow clams that are steamed or salt-roasted to tiny ones the size of a baby's fingernail that are mostly pickled.

In our native Shunde in Guangdong, we have a clam mustard - xianjie - made by pickling shucked clams in salt and Chinese wine. The result is an aromatic sauce that is used for marinating chicken or pork before steaming, or just as a dip on the dinner table.

Yellow clams, white clams, concubine clams, flower clams and finger-nail clams are just a few of the varieties sold in Chinese markets. More exotic seafood offerings may include sea apples, anemones and even starfish. Even some nudibranches, called sea bunnies, are edible.

Chinese cooks are imaginative, and bold enough to venture where many others fear to tread, so no ingredient is too strange to experiment with, as far as they are concerned.

paulined@chinadaily.com.cn