The Common Oyster is also known as the Native Oyster and the Edible Oyster.  It can be found in shallow waters on solid mud, muddy sand, gravel and rocks all around our English coast, although it is not so common in the east and north-east.    It is a ‘bivalve’ mollusc which means it has a soft body enclosed in two hinged shells, like the Grooved Razor Shell and the Common Mussel. 

The Common Oyster can reach a width of up to eleven centimetres and is almost pear-shaped with a rough, scaly shell that has ridged circular lines.   The shell can be a grey-white, yellow-grey or a creamy brown colour with brown or bluish band-like markings on the ridges.  The inside of the shell is a pearly white, yellow-grey or a creamy brown colour with random blue markings.

If sand, grit or a particle of food  gets trapped in between the two hinged shells, the Common Oyster can feel this so it covers the foreign body with a shiny iridescent substance called ‘nacre’ to reduce the irritation.  It repeatedly coats the ‘irritant’ with nacre which eventually forms a pearl. The pearl is often called the ‘Mother of Pearl’ and its size depends on the size of the foreign body that gets trapped inside the shell.