Crassostrea ingens[1] is a species of fossil oyster, a marine bivalve mollusk in the family Ostreidae, the oyster. This species lived during the Pliocene. Fossils have been found in New Zealand shallow-water limestone and shellbeds. Locations include the Wairarapa, Whanganui basin, Gisborne district, North Canterbury, and Hawke's Bay (especially in the Te Aute limestone).
Crassostrea ingens is a giant fossil oyster. It has a shell reaching a height of to over . This shell is biconvex. The left valve is thick and deep, with inflation of to over ; interior cavity depth to over . The right valve is almost flat, to thick. Most specimens curve slightly to the left. The adductor scar area in most Pliocene specimens retains a purplish red colour. Beu and Raine (2009) note that: "This is the sole giant oyster in New Zealand Late Miocene–Pliocene rocks, and there has never been any confusion over the identity of C. ingens."[2]