Description:
Heart urchins, also known as mud urchins, typically do not exceed 2 inches in diameter.  Body color is generally light brown to yellow-brown, and in many specimens, a horseshoe-shaped line of dark red pigmentation partially encircles the central area of the test.  The test is covered with many short spines which increase in length toward the anteriolateral margin, as can be seen in the photo above.  This species also has a well developed frontal notch.

Habitat:
Heart urchins are found primarily on mud or muddy-sand substrates where they may burrow to a depth of 6 inches. 

Range:
Heart urchins range from Bermuda and North Carolina south through Florida, the Gulf of Mexico and the Caribbean to Brazil.  They are found at depths ranging from 0 - 1500 feet, but are most common at depths less than 160 feet.