Crassostrea ingens

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Crassostrea ingens is an extinct giant oyster known from fossil shells in New Zealand. It lived during the late Miocene to early Pliocene, about 2.5 million years ago. Fossils have been found in shallow-water limestone and shellbeds in places like Wairarapa, the Whanganui Basin, Gisborne, North Canterbury, and Hawke’s Bay (especially in the Te Aute limestone).

The shells were very large, reaching 200 millimetres to over 300 millimetres in height. The shell is biconvex. The left valve is thick and deep, about 60–80 millimetres, with an interior cavity depth of roughly 30–40 millimetres. The right valve is nearly flat, about 15–40 millimetres thick. Most shells curve slightly to the left. In many Pliocene specimens, the adductor scar area (where the muscles attached) has a purplish red colour.

Beu and Raine (2009) noted that Crassostrea ingens is the sole giant oyster known from New Zealand’s Late Miocene–Pliocene rocks, and its identity has been clear.

Taxonomy:
- Kingdom: Animalia
- Phylum: Mollusca
- Class: Bivalvia
- Order: Ostreida
- Family: Ostreidae
- Genus: Crassostrea
- Species: Crassostrea ingens
Binomial name: Crassostrea ingens (Zittel, 1864)
Conservation status: Extinct