Marine dwellers, of a predatory nature.
Various examples of Jellyfish, and the Portuguese Man o’ War, which is a colonial organism. It is also quite predatory, equipped with deadly stinging tentacles, which can deliver venom potent enough to kill a human being. Steering clear of the Man o’ War would seem to be a sound strategy. Certain Jellyfish happen to be quite capable of inflicting mortal wounds, as well, however.
A proboscidean, but not in the elephant family. A profound beast of a bygone era.
The crew of the Enterprise enter a bewildering world of compliance to a Being called Landru.