Sea Grub or Sea Mice?
Solomon Islands Currency
You see them in Asian markets. They do look like cucumbers, and are typically about six inches long in the fresh state. Sometimes they are sold dried. The dried form is usually black and rock-hard, and only a few inches long.Despite the name, they are not a vegetable and are not related to cucumbers. They are a kind of seafood.
A common name is Sea Cucumbers, from their shape, also Trepang, or Bêche de Mer, from the French word for “sea grub.”
The Chinese name is hai san 海参 and the Japanese name is namako 海鼠, the characters for which mean “sea mice.”
These primitive sea creatures are a popular food in several Asian cuisines, especially Chinese and Japanese. Their abundance in Philippine waters is one of the reasons Chinese traders first visited Luzon in the Ming Dynasty, which changed history of the region.
B & M: The dried Bêche-de-Mer was such an important trade item in the area around New Guinea that it gave its name to a kind of Pidgin English called B & M. It is used in New Guinea, the Bismarck Archipelago and the Solomon Islands. As Webster says:
“An important commercial item in these islands, its designation thus becoming a type-word designating the pidgin.” — Webster’s Third New International Dictionary 
In zoology these creatures are called Holuthurians; there are more than a thousand species, and the majority are in the Asian Pacific region.
Sea Cucumbers are harvested in the waters off Australia, Alaska and other places in the Pacific region. They are also grown commercially in China, Japan and Vietnam.
Sea Cucumbers have inspired thousands of haiku in Japan and there is even a collection of Sea Cucumber poems translated into English. 
In recent years very attractive Sea Cucumbers have been coming on the market from Chinese fisheries and are sold frozen, in clear vacuum packs, often sorted by color, either all white or all black Sea Cucumbers in a single package.
Nutrition and Health: Sea Cucumbers are low in calories, with only about 70 per 100 grams of the raw state, which also contains
- about 3 percent protein
- significant amounts of sodium (1.3 grams) 
In China and Japan the protein in these creatures is considered easy to digest and to have anti-inflammatory properties. Some researchers in Southeast Asia are investigating possible applications to pharmaceuticals and as additives in cosmetic products.
There do not appear to be any major health concern or risks associated with Sea Cucumbers. In Traditional Chinese Medicine they are considered “neutral” — neither “cold” nor “hot.” TCM uses Sea Cucumbers to manage several conditions, including —
- various neurological conditions 
Bêche-de-Mer in Asian Cuisines: These creatures feature in Chinese, Japanese, Korean and Vietnamese cuisines. And there are a large number of recipes in the Philippines, as you might expect. In the Imperial kitchens of the Qing Dynasty of China, Sea Cucumbers appeared as a stuffing ingredient for dumplings. 
In the Kitchen: Sea Cucumbers live in sandy beach areas or ocean floors, often in areas with coral. As a result, they tend to be sandy, even the raised ones, which are much cleaner than the traditional dried ones.
If you are working with the dry type, you need to soak them well first, at least a day. Then open the body with a single long slit and clean the insides. When they are clean, you can begin cooking them.
After soaking, Sea Cucumbers swell up to eight times their original volume.
Recipes: Beche-de-Mer are often cooked with Bamboo, Mushrooms, Pork or Chicken. In some deluxe recipes they appear with Abalone and Crab. 
For Further Information:
 “Sea cucumber,” article, Wikipedia — http://en.wikipedia.org/wiki/Sea_cucumber
 Webster’s New International Dictionary of the English Language, Unabridged, v.1 (Encyclopædia Britannica, 1976) — http://www.amazon.com/Websters-International-Dictionary-Unabridged-version/dp/0877794685
 Robin D. Gill, Arise, Ye Sea Slugs! (Paraverse, 2003) — http://www.amazon.com/Rise-Sea-Slugs-Robin-Gill/dp/0974261807
 Fumiko Matsumoto, Tadashii shokuseikatsu no tame no shokuhin 正しい食生活のための食品成分表 seibunhyo — http://www.worldcat.org/search?qt=worldcat_org_bks&q=fumiko+matsumoto%2C+tadashii+shokuseikatsu+no+tame+no+shokuhin+seibunhyo&fq=dt%3Abks. Copies in the National Library of Australia and Waseda University Library, Tokyo.
 Yong Yap Cottrell, The Chinese Kitchen http://www.amazon.com/s?_encoding=UTF8&field-author=Yong%20Yap&ie=UTF8&search-alias=books&sort=relevancerank
 Su Chung, Court Dishes of China (Tokyo: Tuttle) — http://www.amazon.com/Court-Dishes-China-Su-Chung/dp/B0046JT0FM
 Chang and Kutscher, An Encyclopedia of Chinese Food and Cooking — good selection of Sea Cucumber recipes — http://www.amazon.com/An-Encyclopedia-Chinese-Food-Cooking/dp/0517506610
Abalone and Sea Cucumbers — http://rasamalaysia.com/braised-abalone-with-sea-cucumber/
Steamed and Stuffed Sea Cucumbers — http://easychineserecipes.org/steamed-stuffed-sea-cucumber-recipe/
Chinese Sea Cucumber Recipes collection — http://chinesefood.about.com/od/shopingredients/p/seacucumber.htm