If you like small elusive crabs, the Porcelain Crab fits the bill. The white ones tend to reside near or in an anemone, using its tentacles as protection. The crab has pinchers and can catch meaty foods, but it also has twin fans that it holds out to trap particulates floating by. A clownfish may tolerate this neighboring crab, but this depends on the fish's territorial attitude. These crabs can be tough to locate in a bigger tank, and once discovered elicits a smile for sure.