Bet you can't guess!!

The mushroom next to it is about one inch wide. It's almost worm like as for it comes in and out of a tiny hole in my live rock. It feeds like a vermetid snail without a tube. From what I've observed it's quite harmless, but I know it's alive, as it oozes in and out of the rock pore. I don't even know where to begin searching the internet as for I don't know where to even classify this thing. Any input would sincerely stop my from going insane trying to google this creature...;D

It hasn't grown in size, nor has it spread. And it appears flesh like rather than spongish,

 

Can't see it in the picture but from your description could be a peanut worm.

 

A little better view....
The "head" is always round and bumpy, but here's a better pic of the neck/body sticking out of the hole....

 

Good guess, but that kind of worm is much too long and a lot faster than what I've got. The previous photo is my little guy extended all the way out.

 

Hmmm?

 

Maybe Priapulida, but the head doesn't look right. Almost looks like a humongous digitate hydroid LOL.

 

LMAO, the scientific community does have a sense of humor. I really couldn't make this up. SushiGirl, I think you nailed it (in every respectable sense LOL)
From Wiki
Priapulida (priapulid worms or ***** worms, from Gr. πριάπος, priāpos 'Priapus' + Lat. -ul-, diminutive) is a phylum of marine worms. They are named for their extensible spiny proboscis, which, in some species, may have a shape like that of a human ***** (the astrics spell out a certain male genitalia)

 

LOL, yeah, they do have a sense of humor! I only found a pic of one kind, but I didn't look really hard either (just one site), so if there are several kinds, that would explain the different shape of the, um, head!