A rare one-in-a-million lobster was caught off the coast of New Hampshire, leaving the fisherman who pulled it out of the water in shock.

Joseph Kramer, 25, was working in New Castle when he pulled in a stunning 'cotton candy lobster' with a unique blue, pink and purple outer shell.

The crustacean's iridescent coloring was either caused by a genetic mutation or its diet, but the different shades also make it a target for predators. 

Rather than risk the lobster turning into someone's dinner or being killed by releasing it back into the sea, Kramer handed it over to the non-profit organization Seacoast Science Center where the crustacean could live out its life. 

Kramer, the owner of the Atlantic Lobster Company, called it a 'once-in-a-lifetime feeling' after he found the cotton candy lobster in the last of his 20 traps while on his boat with his father and girlfriend on Sunday. 

He initially thought it was a one-in-two-million blue crab, but he was later told by the Seacoast Science Center that it was a rare cotton candy lobster.

'This one has a really beautiful kind of a lavender, purple, pink-ish hue to it that puts it right in the cotton candy category,' Sam Rutka, an Aquarist II at Seacoast Science Center told Seacoastonline.

Lobsters have layers of red, yellow and blue carotenoid pigments that are produced by plants and algae that give the crustacean its hue, making them look brown to the human eye.

However, when these pigments over or under-develop they can result in several types of brightly colored lobsters like the one-in-10 red lobster, one-in-50-million two-toned and the one-in-100-million albino.

The crustaceans get these pigments from an antioxidant called astaxanthin - a type of red coloring - that when mixed with the carotenoids, gives off the typical brown hue.

Their coloring turns to red when the lobster is cooked because the heat releases the antioxidant compounds.

But the drastic change in the cotton candy lobster's coloration may come from it having unusually low astaxanthin levels from feeding on a different diet of bait fish, rather than the typical diet of crab and shrimp which are rich in the compound.

'Genetic mutations are a normal part of nature,' Rutka told Seacoastonline.

'These animals, because of mutation, are expressing different color genes in their shells, so that actually makes them more able to be predated upon.

'It's also rare because it's more easily spotted by predators, so that increases the rarity of finding one because it means no one else has found it yet to eat it.'

The Seacoast Science Center reported that it hopes to display the cotton candy lobster at its facility in Rye, New Hampshire within the next two to three weeks.

In the meantime, the facility has placed the crustacean in a quarantine tank to allow it to acclimate to its new environment after its capture.

'I think it is definitely the only one I will ever catch, maybe even the only one I will ever see again in my lifetime,' Kramer told Seacoastonline.

'I'm over the moon about catching it, and letting it be seen by everyone at the Science Center makes it even better.

'Knowing that it will spend its time in safety I think is the best place for it to be kept and preserved.'