Rare blue American lobster arrives at New Hampshire museumA blue American lobster (Homarus americanus) has joined the live collection at the Explore the Ocean World museum in New Hampshire. Researchers estimate the odds of encountering a blue individual of this species at roughly one in two million. Photo: Сакиулова Ольга is licensed under Public domain Синий лобстерHow the color arisesIn their typical state American lobsters wear a greenish-brown shell that blends with the rocky seabed. When astaxanthin binds to shell proteins—including the blue protein crustacyanin—the combined effect produces the familiar camouflage tone. A blue shell appears when rare genetic mutations alter either the amount of crustacyanin or the way it interacts with astaxanthin, shifting the visible color to a saturated blue.