Tomalley (from the Carib word tumale, meaning a sauce of lobster liver), crab fat, or lobster paste is the soft, green substance found in the body cavity of lobsters, that fulfills the functions of both the liver and the pancreas. Tomalley corresponds to the hepatopancreas in other arthropods. It is considered a delicacy, and may be eaten alone but is often added to sauces for flavour and as a thickening agent. The term lobster paste or lobster pate can also be used to indicate a mixture of tomalley and lobster roe. Lobster bisque, lobster stock, and lobster consomme are made using lobster bodies (heads), often including the lobster liver.

Is it true that is it ok to eat the green stuff in a lobster?
yes