Sand piranhas, scientifically known as Excirolana chiltoni, are tiny marine isopods that inhabit sandy intertidal areas along Pacific coastlines. Although their nickname sounds intimidating, these rice-sized crustaceans primarily act as scavengers, feeding on dead animals, seaweed, kelp and other organic debris beneath wet beach sand. When they detect chemical signals from food, they can gather in large numbers and rapidly consume the material. Their feeding contributes to the breakdown and recycling of organic matter, helping nutrients return to coastal ecosystems.