oolite

noun Geology.

1. a limestone composed of minute rounded concretions resembling fish roe, in some places altered to ironstone by replacement with iron oxide.

noun

1. any sedimentary rock, esp limestone, consisting of tiny spherical concentric grains within a fine matrix

n.“rock consisting of fine grains of carbonate of lime,” 1785, from Modern Latin oolites, from oo-, comb. form of Greek oon “egg” (cognate with Old English æg, see egg (n.)) + lithos “stone” (see litho-). So called because the rock resembles the roe of fish.

1. A sedimentary rock consisting of ooliths that are cemented together by calcium carbonate.