Amonitoidea or Ammonitoidea: How To spell?
The word Amonitoidea is misspelled against Ammonitoidea, a noun meaning "An extensive group of fossil cephalopods often very abundant in Mesozoic rocks. See Ammonite."
Ammonitoidea has double "mm" is mispronounced as "m"Remember double 'MM' in between the strings a & onitoidea which should not be misspelled with single 'M'
Wrong Spelling:  a-m-onitoidea  Correct Spelling:  a-mm-onitoidea 
Find more incorrect spellings of Ammonitoidea to spell right way.