[1][5] The Portuguese oyster has a roughly triangular shell, with a maximum length of 10–15 cm.

The interior of the shell is smooth and pearlescent, with a deep cup-shaped depression that holds the soft body of the animal.

[2] The Portuguese oyster is a filter feeder, using its gills to extract phytoplankton and other small particles from the surrounding water.

It is an important ecological species, providing habitat and food for a wide range of other organisms.

This causes gill erosion corresponding with high oyster mortality rates in certain populations.