Turtle Weed

Found in clumps, over shallow waters, on slopes, terraces, and reef tops, of coral and rocky reefs. Looks like long grass.

As many as 9000 species of algae are spread across the worlds oceans, some can be as much as 30 metres across while others are just a slippery scum over rocks.
Algae grows wherever there is enough light and life supporting conditions.
They support a huge number of marine life both for food and as a home.