Initially, the "new" lobster is not noticeably bigger than the "old" one. In the next 15-20 minutes the animal will absorb enough water to inflate the new shell until it is about 30% bigger than the old one, and then re-deposit the stored calcium to harden it. This stiffens the shell and legs to where they are functional again, so that the lobster can walk, swim, and dig, although it will still be soft and vulnerable for several days