Sea urchin shellYour model is disabled. For more details go to Edit properties3D Model
This sea urchin ‘shell’ exemplifies the characteristics of the phylum echinodermata. More specifically, it belongs to the class Echinoidea, which can display perfect pentagonal symmetry. However not all members of the phylum have perfect pentagonal symmetry, with some having a superimposed bilateral symmetry (e.g. sand dollars). The specimen is ~6 centimetres in diameter.