If you have ever opened a whole lobster, you may have noticed a soft green substance inside its body. It may look unusual, but it is not spoiled food or something caused by cooking. Known as tomalley, this substance is the lobster’s hepatopancreas, an organ that plays important roles in digestion, nutrient absorption, metabolism, and energy storage.

Tomalley is typically green or greenish-brown and has a soft, creamy consistency that contrasts with the firmer meat found in the tail and claws. Its flavor can also be much stronger and more concentrated. Some seafood lovers consider it a delicacy and use it in sauces, soups, butter, or spreads, while others prefer to leave it behind.

There is, however, an important reason to be cautious about eating it. Because the hepatopancreas helps process substances from the lobster’s diet and environment, it can accumulate certain contaminants and marine biotoxins. Some toxins linked to harmful algal blooms may remain dangerous even after cooking, so seafood authorities can issue warnings about consuming tomalley from affected areas.

If you are preparing a whole lobster, the tomalley is located inside the body cavity and can simply be removed or left uneaten. Whether it is safe to consume depends partly on where the lobster came from and any current local seafood advisories. Appearance, smell, or a small taste cannot reliably determine whether harmful toxins are present.

So, that mysterious green material inside a lobster is actually a normal organ with a specific biological purpose. Some people enjoy its rich flavor, while others avoid it altogether. If you choose to eat it, checking current seafood-safety guidance for the lobster’s source is more important than judging it by its color or taste.