[SengirV]

a heart? Looks more like an attempt at a deer footprint.

[Wolfstar]

I thought rabbit ears, myself. Also the edges of the carvings look too sharp to have undergone much weathering. That's a very northerly climate given to pretty severe weather. I don't know how long it would take lichen to grow on the surface of the indentations, but I'd venture to guess the carvings are not much older than that length of time.