This five-sided organism is radial as an adult, but bilateral as an embryo. He belongs with sea urchins in the phylum ..........

Chordata Porifera Cnidaria Holothuroidea Echinodermata Echinoidea

and in the class ..........

Ophiuroidea Echinoidea Asteroidea Holothuroidea Crinoidea Concentricycloidea

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