Harvey, my little guinea-pig, has a tiny patch of slightly crusty skin on his nose and I'm confused about what it is. Its basically white, looks like dry skin but its hard and crusty. He's had it since I got him last January and doesn't seem to be making him ill or anything but I was just curious to find out what it may be?

I can post photos of his nose if anyone would like to see it, maybe it'll give a better chance of finding out what it is and how to get rid of it.