Pyrospheres are enemies found in Super Mario RPG: Legend of the Seven Stars. They are located in Barrel Volcano, as well as Bowser's Keep. Pyrospheres usually appear with much stronger creatures in battle, such as Chained Kongs or Corkpedites.
Pyrospheres are the stronger relative of the Sparkys and Fireballs. It is possible they are somehow related to Podoboos or Lava Bubbles.