Someone took a dump in my tank

Found a load of crap in the bottom of the Matchless fuel tank. Just happened to check the fuel level and I could see right to the bottom which looked like the surface of the moon. Dropped a magnet in, nothing picked up so not the steel tank flaking internally. In with the grabber and out comes flakes & shards of a hard resin

I reckon it's what remains of old fuel which resorts to a resin if left for a few years - previous owner must have just put fresh fuel into the tank after a long lay up and give it no thought of cleaning the tank out.

This is what I managed to get out, but tank needs emptying and a thorough job doing as the big flakes are about 1/8" thick. So in the meantime if the bike conks out with fuel starvation I'll know why.