Help with these bleeder screws

So I’m getting ready to pull my demon out of the garage, but wanted to bleed the brakes first as it’s a new car to me and I haven’t gotten my hands on them yet. I got the rear just to eye them up and this is what I found on both sides. I feel as though there should be a screw there, not nubs. Any input on what these might be? Car had a previous life as a strip car. Thanks