I was doodling with a scrap of 2×1 note paper and arrived at what I think might be an original model:
This little snail has a volumetric shell and body, along with some lovely poseable eye stalks.
Originality in Origami is tricksey, as most models recycle techniques from other folds, and the head/eye end uses a fairly standard waterbomb-accordion sink, but I cannot remember seeing it used in this way.
The shell is formed initially by outside reverse-folding the body and as such offers a colour change opportunity if folded with bi-colour paper.
I made a video tutorial if you want to fold it, or read further for a set of photo diagrams.