I have no idea what this is. I've never seen one before. My first guess is that is that it is a slug, but image searching didn't turn up anything.
These were in shaded hardwood forest in northern New Hampshire.
I believe that's an immature stinkhorn, Phallus rubicundus, a common fungus in rotting wood litter (including mulch) in the eastern and southern United States.
The immature specimens will not have the pitted cap on the end, and resemble your picture.
Below are some pictures for comparison:
.................immature specemins......................................mature specemins.................................................