Kildalton Cross is at about 4 km from Dunyvaig Castle and is often considered the finest surviving Celtic cross in Scotland.
The cross has endured for centuries in excellent condition, but something happened in more recent years (possibly 30–40 years) that has accelerated the erosion of the exquisite carvings. These engravings, which were deteriorating naturally from wind, water, and salt erosion, vanished overnight. The offender is supposed to be some kind of lichen or moss. Climate change will exacerbate the rate of this erosion.
https://en.wikipedia.org/wiki/Kildalton_Cross