A slug’s blood is green.

The statement "a slug's blood is green" is true due to the presence of a chemical called hemocyanin in the slug's circulatory system. Hemocyanin is a copper-based molecule that carries oxygen in the blood, giving it a green color. This is in contrast to human blood, which contains hemoglobin and appears red. Slugs have a slower metabolic rate and limited oxygen requirements, and thus their blood does not need to be as efficient as mammals' blood at transporting oxygen.