Marine life|Biscuit sea star from Ammouliani|Chalkidiki|Greece
Peltaster placenta (Müller & Troschel, 1842)

References: National Geographic

The upper surface of the Biscuit Sea Star is covered with many interlocking small plates and six to eight larger plates along the edge of each of their short arms.The Biscuit Sea Star lives on intertidal rocky shores and in coastal waters to a depth of 40 m, feed on sea squirts, sponges, bryzoans and algae. 
