Assertion: sea urchin's test | /r/HasProperty | exoskeleton
Facets:
Source sentences:
text: 17 - Test plates Sections that form the test (exoskeleton).
text: The test of the sand dollar is its endoskeleton—it is called an endoskeleton because it lies underneath the sand dollar's spines and skin, and it is made of fused calcareous plates.
text: 17 - Test plates Sections that form the test (exoskeleton).