This is a broken test of a purple urchin (*Strongylocentrotus purpuratus*) that shows the internal position of the Aristotle's lantern (jaws). For more information on this species see: https://inverts.wallawalla.edu/Echinodermata/Class%20Echinoidea/Echinoida/Strongylocentrotidae/Strongylocentrotus_purpuratus.html