I honestly can't tell what I'm looking at in this pic - do you think you could get a couple of clearer photos? Or could you describe what you're seeing a bit to help out? (stuff like if it moves, how it moves, if it has a shell/two shells or not, if it has a tube, etc. can all be helpful for ID's).
Also, in this specific instance it may actually help to take a pic from slightly farther away/less zoomed in to help give a better idea of the shape.