Jumping Beans

At first, one might think that jumping beans are harmless, or even cute; they are small, and only eat plants.

Description
On Mars, however, things are never as they seem, since plant-eating plantimals actually are the predators in that ecosystem. Jumping beans are highly aggressive to the point of being mean. While they don't do much damage and are easily killed, they usually attack in big packs, making them quite a nuisance.

Jumping beans are usually found near berry patches.