spicule vs spiculum

spicule and spiculum both are nouns.

Word	Noun	Adjective	Verb	Adverb
spicule	Yes	No	No	No
spiculum	Yes	No	No	No

As nouns, spicule and spiculum are synonyms defined as:

spicule and spiculum: small pointed structure serving as a skeletal element in various marine and freshwater invertebrates e.g. sponges and corals

spicule (noun)	spiculum (noun)
small pointed structure serving as a skeletal element in various marine and freshwater invertebrates e.g. sponges and corals	small pointed structure serving as a skeletal element in various marine and freshwater invertebrates e.g. sponges and corals