Oyster shells mobile "three layers"

The common oyster (Ostrea edulis) is a marine bivalve mollusk living. She is also known as oyster. Edulis is Greek for "edible". The animal has long been considered a delicacy. The shell is very dikschalig and variable in shape. Usually more or less round, but sometimes more horseshoe-shaped. The lower shell is a hollow container and the top is flat. Both valves have a very flaky sculpture. On the convex valve are often irregular wavy radial ribs present. On the inside of the shell is clear to see one comma-shaped spierindruksel. The oyster lives rooted to a hard substrate in clear, calm water and salt occurs mainly from the lower littoral zone to approximately 60 meters water depth. The species, however, also maintains itself at greater depths up to several hundred meters water depth. The entrenched immobile lifestyle causes the oyster to the epifauna belong. 

 
Oysters