Due to its unusual body chemistry, A lichen has no need to breathe. It has no eyes, and is therefore impervious to gaze and blindness attacks. It has no mind, and is therefore not detectable via telepathy. It has no limbs and no head. A lichen cannot pick up objects.

The chamber was of unhewn rock, round, as near as might be, eighteen or twenty feet across, and gay with rich variety of fern and moss and lichen. The fern was in its winter still, or coiling for the spring-tide; but moss was in abundant life, some feathering, and some gobleted, and some with fringe of red to it.
Lorna Doone, by R.D. Blackmore