A pair of bioluminescent fungi glows in Brazil's Ribeira Valley Tourist State Park.

In addition to mushrooms, a variety of marine animals as well as select species of bacteria, insects, and annelids (earthworms) are known to be bioluminescent.

Bioluminescence creates "cold" lightemissions with low thermal radiation. An enzyme called luciferase triggers a pigment called luciferin to oxidize, and the reaction emits light.

But why the fungi evolved to glow this way remains a mystery, the University of Sco Paulo's Stevani says.

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