/ ˈæmənaɪt; NAmE / noun
[ C ] a fossil of a simple sea creature which no longer exists, and which was related to snails
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WORD ORIGIN
mid 18th cent.: from modern Latin ammonites , from medieval Latin cornu Ammonis horn of Ammon, from the fossil's resemblance to the ram's horn associated with Jupiter Ammon, whose temple is found at Siwa in Egypt.