Magmag

Slugma is a limbless gastropod mollusk Pokémon composed of magma. Its body is bright red, fading to a duller red along its extremities. It has large, round, yellow eyes with small pupils. Slugma's head is ovoid with flame-like extensions spreading upward from its eyes and round, stable drops of magma dangling from its upper jaw. Its lower body is irregular in shape, and occasionally emits bubbles.

Slugma's circulatory system is composed entirely of magma, which delivers vital nutrients and oxygen to its organs. To prevent its body from cooling and hardening, Slugma neither sleeps nor ever stops moving. If its body does begin to cool, it will become brittle and may break apart. Slugma constantly seeks warm places and gathers with other members of its species in mountains and volcanoes. Slugma takes magma baths to heal itself. It is believed that when volcanoes were more active in ancient times, Slugma were seen more often.

Evolution
Slugma evolves into Magcargo.

(Source: Bulbapedia)