fox fire
noun
: an eerie phosphorescent light (as of decaying wood)
also : a luminous fungus (such as Armillaria mellea) that causes decaying wood to glow
Example Sentences
Recent Examples on the Web The northern lights are referred to in Finnish as revontulet, which literally translates as fox fire. 
David Nikel, Forbes, 28 Mar. 2022
David Nikel, Forbes, 28 Mar. 2022 Word History
First Known Use
15th century, in the meaning defined above