Once worn on heads of bad eggs in corners. On necks of best friends, to prevent the gnaw, sorry, doctors orders. A deadly snail, although slow, likely pierces into toe. A cold treat hold. Flipped its in the road. A pronounced voice distorter.

What did Tennessee? The same thing that ...

With mouths wide open, they unselfishly loved humankind.

Found in a gym, helps strengthen a back Found in a floor, can help cover a room Found in politics, a stand which to yack Found on a ship, sends a pirate to doom

I may, or may not exist on a material plane, but I am the one who divides the space, and The one who stops everyone from moving forward. What am I?