Hi there we just noticed we have a visitor in our small back yard fountain pond like 25 gallon LOL it is about 8 inches wide has a smooth shell and long tail on the very back of the shell is is ridged or spike like ? we watched it last night get out of the pond walk around a bit then got back into the pond there are no fish in it so not sure why it would be in there ..nothing really for it to eat other then maybe some plant algae and some fallen leaves from a maple tree lol I think it is a snapping turtle but when it was out and when I tried to see it in the pond it never showed any aggresion ? We live in Indiana if that helps to know what type it is? TY