Llyrian Tree

This large tree seems out of place in this underground chamber, though it appears to be thriving on the light coming in through the ceiling. When the party originally found it, it was stone, though they were able to restore it to its wooden form using a gastrolith. It has brownish bark and gray-green leaves.
It's not clear how the tree was turned to stone in the first place, since it doesn't have eyes, but it's noted in the TreeKeeper's notes to be an unusual specimen.
This appears to be the same kind of wood used to make the wooden lantern.