This is a Stachys. It's a little silver-leafed plant. Don't confuse it with a stack. That's a big pile of amps. Stachys is also called 'lamb's ears'. I think it's a tribute to something Ozzy ate on stage in about 1982. Also because it's sort of hairy.
"It scrambles everywhere and roots into almost anything. We had a drummer like that once. Lost him in Hungary. Last seen getting into a minibus full of nuns. He was naked from the waist down. They seemed quite pleased. Never heard from him again. Frankie, if you're watching this, we left your trousers at the British Embassy."