Brown stuff attached to base of leather


I acquired this Fiji leather from a LFS and found that it has some brown stuffs on the base of it. My snails are feeding on it. What would it be?
I'd almost say it was tissue necrosis in the leather, but it almost looks like an algae of some kind. Can it be gently scraped away at all?
Yeah that looks odd. The striations are not in the same direction as those of the leather, so it may not have been associated with the leather itself. One possibility that came to mind was that the leather used the remnants of a shark/skate/ray egg to attach its foot. The fibrous protrusions at the top edge stere me away from algae
Yea it looks like brown wafer algae Lobophora.

The weird part is the bubble bee snails there and maybe it is just coincidence. if it is some thing other than algae they may be cleaning it up.