Reminds me of a Terry Pratchett quote:
Here and there huge patches of fungi, luminous with decay, cast a faint glow over the ancient stonework.
[Footnote: It didn't need to. Cuddy, belonging to a race that worked underground for preference, and Detritus, a member of a race notoriously nocturnal, had excellent vision in the dark. But mysterious caves and tunnels always have luminous fungi, strangely bright crystals or at a pinch merely an eldritch glow in the air, just in case a human hero comes in and needs to see in the dark. Strange but true.]
DreamMaster.