Though a comparatively common sight along Hawaiian beaches, green sea turtles are listed as a federally threatened species. These turtles can average between 150- 400 pounds in weight (68- 181 kg). Unlike the rarer hawksbill turtles, green sea turtles have a rounded head. The plates on its shell grow together like tiles and do not overlap. An estimated 200,000 adult female green turtles exist today, down from a one time population of tens of millions. When spotted, they are often feeding on limu and algae that grows on coral and near-shore rocks, or basking in the sun at the water's edge.