I found a rather strange invertebrate...something... outside my home this evening, and I have no idea what it might be. It looks kind of like a small brown lobster, without the claws. I think it has 8 legs, making it an arthropod(?), but if I've misidentified that, please correct the tags. It's 4 or 5 inches long, head to tail. It was found in south-eastern Massachusetts. Potential nearby habitats are open grassy fields, a forest, and a cranberry bog, if that helps.
The picture is kinda fuzzy, I think the video is better.