All about Mang-Da

Last week my aunt came from Hongkong for visiting us with her son and her daughter in law. (We have to speak to each other in English because my cousin is not Thai so he can not speak Thai) We went to Khao Yai and Pak-Chong. On the way back, we dropped down to have lunch at the market in Singburi. While we were walking around the market, my cousin had seen some kind of animal in the bottle and asked me what is it? It is Mang-Da but how to say that? I just learned about Mang-Da in last week. But It is not the same one. The Mang-Da that I had learned is the Horseshoe crab but this one is not the horseshoe crab. Thai people also call it as a Mang-Da. Then I answered my cousin that it an animal that eatable. He asked me how its test? Actually I don't know so I said that I don't know but I just know that Thai people mix it with the food and it give the smell. Funny is, I go to ask his mother(my aunt) I wish that she would had the answer for her sun in Cantonese. But she said that she also don't know. There is no this kind of animal in Hongkong. Then She said to her sun that it for eat. Finally my cousin has a conclusion for himself that "It is a Thai cockroach because it looks like a cockroach!" .... His conclusion is made me laugh (Who gonna want to eat the cockroach?) ....

Now I still don't know what to call this kind of animal in English. I have search for more information in the websites. I could see just the Horseshoe crab(which is not the same one as I mean) and the pimp(which is not refer to an animal but it is a kind of people) ... Or it actually be the cockroach? a kind of cockroach....