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