Lava

Lava is molten rock that has been expelled from the interior of some planets and some of their moons. Magma is generated by the internal heat of the planet or moon and it is erupted as lava at volcanoes or through fractures in the crust, usually at temperatures from 700 to 1,200 °C (1,292 to 2,192 °F). The solid rock resulting from subsequent cooling is also often described as lava.

Burny is the only marshmallow who specifically has the power of Lava.