Dry is not a problem, preferable really, because that is the typical state of a lichen. They are “designed” to dry out very rapidly once humidity fall below a level at which they can successfully photosynthesize (some manage it as low as 80% relative humidity!) But beyond that, they want to dry out as quickly as possible to go into suspended animation so they can survive until the next time humidity is available.
As in last observation, you need to see the lower surface at very least. Also helpful to know the substrate: is it calcareous? e.g. dolomite? Can check with drop of HCl. If it bubbles it is calcareous.
