What is "brain mushroom"

n. A fungus common in Europe and North America and one of several species of fungi known as false morel, ''Gyromitra esculenta''.

n. a poisonous gyromitra; the surface of the fertile body is smooth at first and becomes progressively undulating and wrinkled (but never truly pitted); color varies from dull yellow to brown [syn: Gyromitra esculenta, beefsteak morel]