phragmocone vs phragmacone

phragmocone and phragmacone both are nouns.

Word	Noun	Adjective	Verb	Adverb
phragmocone	Yes	No	No	No
phragmacone	Yes	No	No	No

As nouns, phragmocone and phragmacone are synonyms defined as:

phragmocone and phragmacone: the thin conical chambered internal shell (either straight or curved) of a belemnite

phragmocone (noun)	phragmacone (noun)
the thin conical chambered internal shell (either straight or curved) of a belemnite	the thin conical chambered internal shell (either straight or curved) of a belemnite