I suppose that technically, they are probably a tortoise. I haven't seen them, almost never do. They hide in burrows they make in the mulch I have in the garden. Last summer, after most of the garden had died down, I took my mower in there and started chopping weeds down. I found one that way when the blade whacked it on the back. I thought I'd hit a rock. He was shook up, but still okay, and I relocated him outside the fence.

Earlier this growing season I found a gap in my fencing where the gate is hinged. I suspect one found their way in through that this year.

They eat my cucumbers, take bites out of low hanging tomatoes, munch on my melons, and most anything out there. Rabbits sometimes get in there too, but a turtle will gnaw a 2 or 3 inch hole in the side of a melon and then eat all the yummy insides and leave nothing more than a shell with that hole in it. They can stretch their necks pretty darn far when they want another bite of a cantaloupe

I'm always looking for their dens, if I find one I'll snap a pic and post it.