The crab above is mainly decorated for camouflage but has moved onto a black sponge. The crab below has decorated himself with a sponge which is highly toxic. This is known as Aposematism. The poisonous sponge signals to predators that the prey is toxic. This signal is beneficial to both the prey and the predator. It protects the prey and tells the predator that the prey is toxic thereby protecting it as well.