Marine Invertebrate in a Spiny Shell
Puzzle 10 of Day at the Museum Easy Pack
Question is: Marine Invertebrate in a Spiny Shell
and the answer is: SEAURCHIN
Word Meaning:
SEA URCHIN — Any of many marine echinoderms, of the class Echinoidea, commonly found in shallow water, having a complex chewing structure named Aristotle's lantern.
Definitions from Wiktionary.