Hi!! I got a couple of Lithops, living stones, about a week ago, i repotted them into a mixture of soil, perlite, sand and pea gravel into a shallow dish with the plant portion sticking out. I was being nosy to my plant and noticed this weird spot on one of them. If anyone can give me any tips, suggestions, advice, or diagnosis that would be appreciated!!! *I pictured the dish below with the other ones