Oolite

from The Collaborative International Dictionary of English v.0.48

Oolite \O"o*lite\, n. [Gr. w,'o`n an egg + -lite: cf. F. ooithe.
   So named from its resemblance to the roe of fish.] (Geol.)
   A variety of limestone, consisting of small round grains,
   resembling the roe of a fish. It sometimes constitutes
   extensive beds, as in the European Jurassic. See the Chart of
   {Geology}.
   [1913 Webster]