Why are they a horror-staple?

[timbershiver]

So what's the big deal about Tentacles?

I just can't find them creepy.

Not Kraken, not Cthulu, not anything tentacly.

Cute, yeah (Have you seen how awesome Octopii are?)  (like, really awesome)

Spooky, no.

So I was really disappointed to find out that the Slender Man had tentacles.

I dig his suit and M.O but he just doesn't do it for me now :(