A blue lobster from the tank at the Kittery Point restaurant Pepperrell Cove is seen in this Seacoast Online photo before being released into the ocean in 2018. Credit: Rich Beauchesne / Portsmouth Herald

A fisherman at a seafood co-op in Vinalhaven caught a rare blue lobster, according to a tweet from CBS affiliate WGME on Tuesday.

How rare? The blue crustaceans occur in nature once for every two million normal lobsters. A protein imbalance causes the odd coloring, according to National Geographic.

New England fishermen seem to net blue lobsters every few years. One blue lobster could have been eaten at a Maine restaurant in 2018, but it was set free when customers insisted. Another, found in Massachusetts, became part of an exhibit at New England Aquarium in Boston in 2012. A Maine teen caught one in New Hampshire in 2014.

Other colors are even more rare. One in every 10 million lobsters has a red shell and one in about 30 million is yellow. Possibly the rarest, albino lobsters occur once in 100 million, according to the University of Maine’s Lobster Institute. One of those came into Portland with a catch made off the north side of Chebeague Island in 2017.

Watch more: