In the basement, behind a piece of drywall, behind the toilet, lives a very dark black spider. He is fat legged, not skinny, and I can't see the underside of him/her. I only see this spider once in a while, and only at night. It is fast. I try to get it and it runs back under the drywall. Then, over by the door leading to the garage, I noticed another one that looked the same, only a smaller version. Again, by the time I got something, and started near it, he ran into the garage. By the time, I got the door open I could not find it. What kind of spider does this sound like?