Plagusia squamosa

Plagusia squamosa is a marine crab of the family Plagusiidae, formerly considered a subspecies of Plagusia depressa (as P. d. tuberculata). It is found in tropical Indo-Pacific oceans. P. squamosa's carapace is bumpy and quite coarse, seemingly scaly, leading to its common name: The Scaly Rock Crab.

They are also commonly referred to as "rafting crabs" due to their propensity to live on pelagic marine animals such as sea turtles-- most notably olive ridleys (Lepidochelys olivacea). They characteristically cling and float on organisms or objects. It is still not fully understood of the relationship shared between the crabs and the sea turtles, though it can be hypothesized that the relationship is either mutualistic or commensalistic.