Apparently not content to stop by wrapping itself around your chest, the tentacle begins to travel downward. You shudder from the sensation of it propelling itself down your body, until finally it stops just atop your gut, completely motionless. For a moment you figure that maybe it's actually finished and about to die from being separated for so long, but your luck (unsurprisingly) simply isn't that good and it soon begins stirring to life again, lifting a tip up off of your stomach before arching it back down and pressing it against your navel.
You feel a pressure as it pushes harder and harder, shoving itself at your belly button. The pressure soon begins to border pain, but just before it starts to become truly painful you feel a weird sort of POP, something like bubble wrap, and then the unpleasant sensation of the slithery snake-like creature sliding into you. In a last-ditch effort to stop it you grasp at its "tail" and pull once again, but it simply slides out of your grip and into your gut, leaving your belly button looking no worse for the wear.
For several seconds, you can feel the tentacle slithering about inside you, moving itself around and sliding along your innards. The sensation is both extremely unfamiliar and extremely disconcerting, like a snake making its home in your insides, but perhaps the most disturbing part is when it finally stops. If it's not moving, there are only two possibilities: either it's died and you now have a dead organism sitting inside you, or worse - it's still alive.