1. a marine animal of the class Echinoidea, including sea urchins and sand dollars
Usage: zoology

1. relating to or resembling echinoderms of the class Echinoidea
Usage: zoology

Examples

• The echinoid fossil showed the characteristic spiny structure of ancient sea urchins.
• Marine biologists collected several echinoid specimens from the tide pools.
• The echinoid shell was perfectly preserved in the limestone.
• Students examined echinoid anatomy in their marine biology class.
• The echinoid features were clearly visible under the microscope.
• Fossil echinoids are common in Mesozoic rock formations.