Wondrous Item, Common
A horn cage of grown chitin holds a knuckle of pale lumewort that will not die so long as it drinks the spore-air of the Deep at least one day in seven. It sheds Bright Light in a 20-foot radius and Dim Light for an additional 20 feet.
Kindled Bloom. As a Bonus Action, you can raise the light, lower it to a candle's glow, quench it entirely, or shift its color to any hue you have seen. Left in ordinary air too long, the lantern dims to a candle until returned to the Deep.
Source: Sporebound