Atlantic Thorny Oyster GALLERYSpondylus americanus
The unmistakable thorns on this bi-valve's shell gives it it's name. It is often covered with other organisms that attach to it's shell. The Oyster itself attaches one side of it's shell to a surface and filter feeds from the water flowing through it's open shell. All these pictures were taken in water between 2 and 6 feet deep.