Note:
Beam trawls used in the Transect Program do not adequately
collect burrowing organisms,
so the distribution and abundance of this species is not well documented.
This massive, heavy, red-brown
burrowing echinoid is a type of heart urchin.
The dense covering of short, stout spines aid in the organism's mobility beneath
the sediment surface.
On the Charleston Transect it was only collected using a dredge, suggesting
organisms were buried.
Test length is ~18 cm -- as long as a person's hand!
The pentagonal (5-pointed) radial symmetry is easy to see, however this species
is
characterized by having only 4 petals, which are depressed rather than raised.