Weird Indicator on Super Corsa tyre

[redback911]

Folks, my buddy is seeing this weird mark on his Pirelli Supercorsa after some track use:



I did a quick Google but failed to find anything. It looks like a wear indicator, or treasure map?

[redback911]

I asked him for more piccies. He mentioned there are several of those marks. He is supposed to ride at Spa tomorrow so just a bit apprehensive.