Sea cucumbers [the Hawaiian name is weli or loli ] are bottom-dwelling marine creatures that are our “reef janitors”. They are filter feeders and sift sand for the organic coating on the sand grains. They also have a defense mechanism that is quite unique and not something you would want to try at home. They essentially vomit their entire insides (organs and all!) to escape from predators. After avoiding a predator in that fashion, their insides regenerate in a few months.