noun🔗ShareAn animal of the phylum Echinodermata, comprising radially symmetric, spiny-skinned marine animals including seastars, sea urchins, sea cucumbers, crinoids, and sand dollars."During our visit to the aquarium, we learned that echinoderms, like starfish and sea urchins, have a unique radial symmetry. "animalbiologyoceannatureChat with AIVocabulary GamePractice Reading