Sandalolitha
Sandalolitha is a genus of sea urchins belonging to the family Sandalidae, a group of irregular sea urchins commonly known as “heart urchins”. The genus contains a single species, Sandalolitha quadriformis, found in the waters of the eastern Atlantic Ocean, the Mediterranean Sea, and the Black Sea.
Common Names
Sandalolitha quadriformis is commonly known as the "four-sided sand dollar" or the "four-holed sand dollar". These names refer to the distinctive shape of the urchin's test (skeleton), which is nearly square and exhibits four prominent openings or "pores" on the oral (under) surface.
Characteristics
Sandalolitha quadriformis is a small, flattened sea urchin with a test measuring around 2-4 cm in diameter. Its distinctive shape and four-pore arrangement distinguish it from other sand dollars. The oral surface of the test has a central mouth surrounded by a series of tube feet, which are used for locomotion and feeding. The aboral (upper) surface is covered with spines and is marked by a circular, slightly raised area known as the periproct, which contains the anus. The test is covered in short, dense spines, which are usually white, gray, or brown in color. The species exhibits a distinct, symmetrical pattern of plates on its test.
Environment
Sandalolitha quadriformis is a benthic species, meaning it lives on the seabed. It prefers sandy or muddy bottoms, typically in shallow coastal waters with depths ranging from 10 to 100 meters. The species is common in the Mediterranean Sea and is often found in association with seagrass meadows and other benthic communities. The four-holed sand dollar is considered a deposit feeder, meaning it gathers food by filtering organic matter from the sediment.