When you open a whole lobster, you may find a soft green or greenish-brown substance inside its body. This is called tomalley, and it is not leftover food or something caused by cooking. Tomalley is actually the lobster’s hepatopancreas, an organ that helps with digestion, nutrient absorption, metabolism, and energy storage.

Tomalley has a creamy texture and a much stronger seafood flavor than the familiar meat found in the lobster’s tail and claws. Some seafood lovers consider it a delicacy and use it in sauces, butter, soups, or spreads. Others prefer not to eat it because of its unusual appearance or intense taste.

There is also an important safety concern. Because the hepatopancreas processes material from the lobster’s food and environment, it can accumulate certain contaminants and marine biotoxins. Some toxins linked to harmful algal blooms may survive cooking, which means preparation alone does not always make contaminated tomalley safe.

For this reason, seafood safety authorities may advise people to avoid tomalley from lobsters caught in areas where toxin levels are elevated. “Color isn’t a reliable test. Smell isn’t a reliable test. And tasting a little bit isn’t a good way to find out.” Checking current local seafood-safety advice is more reliable than judging tomalley by its appearance or smell.

If you are preparing a whole lobster, the tomalley can simply be left untouched. You do not have to eat it, particularly if you are unsure where the lobster came from or whether there are current safety warnings. Tomalley is a natural part of the lobster, and skipping it does not affect your ability to enjoy the tail and claw meat.