coral {noun} /ˈkɒr(ə)l/

a hard stony substance secreted by certain marine coel­en­te­r­ates as an external skeleton, typically forming large reefs in warm seas.

a sedentary coel­en­te­r­ate of warm and tropical seas, with a cal­care­ous, horny, or soft skeleton. Most corals are colonial and many rely on the presence of green algae in their tissues to obtain energy from sunlight.

plus under­wa­ter antlers, of course.