Oolite Wikipedia
Oolite or o 246lite egg stone is a sedimentary rock formed from ooids spherical grains composed of concentric layers The name derives from the Ancient Greek word ᾠόν for egg Strictly oolites consist of ooids of 0 25–2 millimetres diameter rocks composed of ooids larger than 2 mm are called pisolites The term oolith can refer to oolite or individual ooids