Hi- We found these odd shaped indentations on a step outside the house during the last snowfall (we live in south eastern Ohio). There are no tracks leading up to them to indicate an animal cause. The only explanation we've been able to come up with is icicles that fell and melted, but the edges are so distinct that even seems unlikely. There was nothing on the step prior to the snowfall (i.e. solid object, salt, etc) Any ideas?