"limestone rock consisting of fine spherical grains of carbonate of lime," 1785, from Modern Latin oolites, from oo- "egg," + Greek lithos "stone" (see litho-). So called because the rock resembles the roe of fish. Related: Oolitic.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit vih, Avestan vish, Latin avis "bird;" Greek aietos "eagle;" Old Church Slavonic aja, Russian jajco, Breton ui, Welsh wy, Greek ōon, Latin ovum, Old Norse egg, Old High German ei, Gothic ada all meaning "egg."
<a href="https://www.etymonline.com/word/oolite">Etymology of oolite by etymonline</a>
Harper, D. (n.d.). Etymology of oolite. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/oolite