My sister's cat Mouse has another claw, well it's not really a claw, it's kind of like a claw but harder, thicker and not pointy, growing out of the toes of all his feet. My cat Blue (his brother) only has one of these claw-like things out of one of his toes. Does anyone know what this is or what could cause it? I'm pretty clueless, I've never seen it before. Please help me in any way that you can because I'm worried. I know it must be causing them pain.