Every hero has to have his weakness. For some people, it’s chocolate cupcakes. For other’s, it’s a piece of rock. Call it bad luck that there seems to be a never-ending supply of rocks from Superman’s home planet to turn up and give him grief. At least they’re a pretty color. The most common type of Kryptonite is green, just like these socks, which have a crystalline pattern to show off your superpowered knitting skills.