Arrow Crab
The Arrow Crab is a nocturnal creature that has eight spider-like legs. These legs can be more than three times the length of their carapace (body). The females are dramatically smaller than the males. They can live on small particles of food and fish waste but should be fed meaty food to supplement their diet. As an extra added bonus, these are a known predator of bristle (fire) worms, and thus are popular amongst hobbyists who don't want these worms. They should only be one to a tank because they can become territorial with their own species. They have been known to prey on feather dusters and some corals, especially when they get hungry, so use caution if adding to a reef aquarium. Ensuring they have enough food will help to prevent them from picking on other desired inverts.