Lobsters come in just about every color but red. The shade varies a little from lobster to lobster, but they are a dark blue-green when alive. Live lobsters are greenish brown-black because of many different color pigment chromatophores. When they are cooked, all the pigments are masked except for astaxanthin, the red background pigment. The red pigment is the most stable component of the coloring in a lobster. The greens and browns which darken the shell in a live lobster are destroyed by the cooking process.
Fishermen have been known to bring in blue, yellow, red and spotted live lobsters. Usually, when lobsters are hard-shelled, their shells are a darker color. Also, when you cook hard-shell lobsters, their shells will turn a brick red color and sometimes black, whereas soft-shelled lobsters, when cooked, are a bright red color.