Symbiosis

Clownfish and anemones live in harmony. The venomous cells from the tentacles do not harm the fish, which become immunised while they are young. Anemone tentacles are a safe haven for clownfish to hide from predators.
Interestingly, the daring clownfish will actually leave the safety of this environment and will face its predator out in the open! This, of course, is nothing more than a "cunning plan" to lure the predator closer to the anemone's tentacles.

Anemones, corals and jellyfish
Carpet anemone (Stichodactyla haddoni - Stichodactylidae) 

Grape coral (Euphyllia divisa - Euphyliidae) 

Mushroom anemone (Discosoma sp. - Discosomatidae)

Bony fish
Clown anemonefish, common clownfish, false clown anemonefish (Amphiprion ocellaris - Pomacentridae)