From the Super Mario Wiki
Lava Ghosts, also known as Spark Spooks, are ghosts made out of fire in Yoshi's Story with gaps in the flames that forms eyes and a mouth. They appear in Blargg's Boiler, where they leap out the lava trying to hurt Yoshi. Whenever they jump out of the lava, they make a strange moaning sound. Lava Ghosts are very similar to Podoboos in both appearance and function and even their Japanese names are similar, Podoboo (Baburu) and Lava Ghost (Flare Baburu).