Roper
The Roper is an iconic Dungeons & Dragons monster; an ancient entry to the game, it is the most long-lasting of the plethora of "killer shit in disguise" monsters that proliferated during the days of Advanced Dungeons & Dragons.
In a nutshell, a roper is a predatory aberration that resembles an outcropping of rock with one eye, a giant mouth full of teeth, and long, sticky tentacles it uses to grab victims and drag them into range of its mouth.