Coin Green Seaweed

Halimeda gracilis is a species of calcified coenocytic green algae. It has a coenocytic thallus constructed of a system of interwoven bifurcated siphonous filaments that expand into utricles at the thallus surface. Macroscopically, the thallus is characterized by a series of green articulated coin shaped segments made rigid by the impregnation of calcium carbonate as aragonite. The calcium carbonate released from dead Halimeda seaweeds are said to make major contributions to sand in some areas such as the Bahamas and the Great Barrier Reef.