The Collaborative International Dictionary
Sea ginger
Sea ginger \Sea" gin"ger\ (Zo["o]l.) A hydroid coral of the genus Millepora, especially Millepora alcicornis, of the West Indies and Florida. So called because it stings the tongue like ginger. See Illust. under Millepore.
Wiktionary
sea ginger
n. (taxlink Millepora alcicornis species noshow=1), a coral with a calcareous skeleton.