Which animal forms large, floating mats on the sea surface for communal living and protection?

Sargassum frogfish

Who were the Greek goddesses of inspiration in arts and sciences? In the sitcom "The Office" (U.S. version), who is the regional manager of the Scranton branch? In Olympic gymnastics, how many apparatuses do men compete on? What rap group featured Ice Cube, Eazy-E, and Dr. Dre? Who was known for coining the political concept of the 'Social Contract'?