What is the X in X-mas?
jellyfish jel·ly·fish (jěl'ē-fĭsh')
n. pl jellyfish or jel·ly·fish·es
Any of numerous marine coelenterates of the class Scyphozoa, some poisonous species of which notably the Portuguese man-of-war, produce a toxin that can be injected into the skin by nematocysts on the tentacles, causing linear wheals.
Any of various similar or related coelenterates.