Of course, not everything in Mario's way is that benign. Some of the flora and fauna of the Super Mario universe is downright deadly.
Piranha plants exist in real life too. At least Venus Flytraps do, and that's pretty much the same thing. They eat flies and other small insects.
Unfortunately for the platform gamers amongst us, the Nintendo variety eat plumbers too.
I was quietly amused and delighted by the prospect of a pipe toy above. This is yet another one, but with extras. I'm just pointing this out, in case those reading know nothing about the game. That's not a plant-pot under the piranha plant.
The natural habitat of your average piranha plant is a pipe. They live in them, pop their heads out at regular intervals and shoot fireballs at passing plumbers. Evolution is a wonderful thing.