Nightlight

Nightlight was a fungus that grew in the Underdark. It glowed with bioluminescence and was sensitive to being touched by creatures or objects.

Description
Nightlight had tall stalks ranging from five to ten feet (1.5–3 meters) when mature. The tube-like stems glowed with a bright light out to a distance of fifteen feet (4.6 m) and provided dim illumination for another fifteen feet (4.6 meters) beyond that. This mushroom was sensitive to touch and would extinguish its glow when first touched by a creature or an object. Touching it again caused the glow to reappear. If the fungi were uprooted, killed, or destroyed, the glow faded away forever after a few seconds.