It is shown that expansible ettringite forms in the topochemical reaction,and crystallizes in-situ on the surface of unhydrated aluminate minerals and orients radially.
Sea cucumbers are members of the phylum Echinodermata, along with sea urchins, starfish and other radially symmetrical, " spiny-skinned" marine invertebrates.
The first radially symmetrical echinoderm known from the fossil record is Camptostroma, which showed up between 516 and 513 million years ago in Pennsylvania.