Part 321932 is a thermostat gasket (i.e. a seal used with the thermostat housing) in outboard / stern-drive cooling systems. 

Some aftermarket listings describe it as a cork gasket for a 90 °C V4 crossflow thermostat. It is said to replace or be interchangeable with 18-0675, 12-F658504, and 321932 in certain applications.