Bummer...nobody got my joke. A sea urchin skeleton is called a "test".....
That's what I like about this site - you can learn so much 'valuable' information....
From
http://www.oceaninn.com/the-nature-preserve/echinoderms/
The skeleton of a sea urchin, known as the 'test', is a rigid shell made of flat and fused calcareous ossicles. The test is divided into ten sections, extending from the mouth on the bottom to the anus on top. Five of the sections, known as the 'ambulacral' plates, are pierced with holes through which the tube feet protrude. The five plates without the holes are known as the 'interambulacral' areas.