Is it a tear or cut? I haven't heard of a cut opening. If it's a tear, especially on the foot, its chances of survival are very low.
I would also provide a rock for it to plant its foot on. It doesn't look very comfortable on the egg crate. Counting the holes in the eggcrate, and assuming it's standard eggcrate, is the nem less than 3" across? if so, it's definitely very unhappy. Give it good light and decent flow -- not too much where it's getting whipped around but enough so that it can help the nem facilitate any waste removal.