According to Wikipedia:
“Around one in two million lobsters is blue.
A research study conducted by Professor Ronald Christensen at the University of Connecticut discovered that a genetic defect causes a blue lobster to produce an excessive amount of protein. The protein, and a red caratenoid molecule known as astaxanthin, combine to form a blue complex known as crustacyanin, giving the lobster its blue color.
I must have lobsters that match my powder blue chambray linen!