I noticed a strange lump on my cat today as I was giving him some attention, I parted his fur to discover a strange solid lump, grey in colour on his stomach. I've never seen anything like it before! As it's something that concerns me we'll take him down to the vets first chance we get to have it checked out, i've taken a picture of it if anyone can help determining what it could be...

It's not terribley large but feels quite high raised!