What is it?

I lifted and potted my geraniums and brought them indoors over the winter so that I can take cuttings in January. I keep looking at and around the plant pots in case anything crawls out of them onto the floor! Today I saw this leaf which is encrusted with "things". I wasn't sure whether it is a sort of fungi or lichen or larvae of some sort.

Whatever it is, is now back in the garden where I put it after I added colour to the blip.