Perna viridis (Linnaeus, 1758) has been accidentally introduced from New Zealand to the East Coast of the USA, part of the Caribbean Sea, and the Gulf of Mexico. This species grows to about 90 mm (about 3.5 inches). The ventral (“lower”) margin of the shell is straight or slightly concave, the posterior end rounded. The periostracum may be very flaky in dried shells. The shell is brown externally with green tinges at and around margins. The shell interior is nacreous, whitish or light-purple.
