The stonefish looks like a stone, just like the reef that it lives on. It also like to sit on the sandy seabed. It has spines, though, that it uses to defend itself. They are very sharp and contain a nasty venom which can be very painful and sometimes lethal. To avoid the stonefish's nasty sting, you mustn't touch the reef while swimming and you should make sure you always shoes or sandals when walking in shallow, sandy water.