If you thought Black widows are just a snazzy character in a superhero franchise, you need to get out more! Except outside is where you'll find actual Black Widows, with venom 15x more deadly than a rattlesnake. Actually, you'll find them inside too. Not to freak you out or anything.
In Scottish folklore, the Kelpie will appear as a horse or a human in the water, and lure people to their demise! I would like to note that this particular Kelpie won't magically turn into a human while you're cuddling it. Or try to tempt you to a watery grave. Which is good.
Sit on a chair! Sit on a throne! Sit on this...toadstool? While a "stool" does sound like a comfy place to put your rear, in this particular case you would also be smooshing a cute little amphibian. So don't do that.