Echinoderms ( literally "spiny skins" ) are among the strangest animals on the planet. They start out as bilaterally symmetric larvae but grow into a 5-way body symmetry as adults. Some species show six, seven, or even higher levels of symmetry. Worm-like Sea Cucumbers have re-evolved a bilateral body plan over the underlying 5-way plan. Because of certain developmental traits, it is felt that despite their strangeness, echinoderms are actually more closely related to chordates than any other group.
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