Yesterday, I was at work by myself in the weld shop about 2:45pm. The weld shop is maybe 60ft x 60ft total. Kinda small. My one coworker had already went home early and the other was in the machining shop talking to another coworker. I was alone. ALL shop fans were off, ALL welding machines were off so it was library quiet. ALL 3 doors to the weld shop were closed tight. It’s very bright in the weld shop due to the floured lights Yet something/someone dark dark green ducked down very QUICKLY behind a portable green Welding Curtain. (attempting to camouflage oneself?) The portable weld curtain is 6ft tall so what I briefly saw had to be about 6 & 1/2 ft tall & was real dark green. Olive drabish. It seemed like it had been peering over the top of the welding curtain (looking my way) as I was walking towards that area then it ducked down behind the welding curtain attempting to hide. Nothing was there though. I rapidly checked the entire small weld shop but I was alone. Yet I know DAMN WELL I saw something tall & dark green move lightning quick in a downward motion ducking behind that welding curtain. This was not out of the corner of my eye, but directly in front of me about 20ft in front of me to be exact. Oddly enough in the last 4-5 days All of the podcast I've been listening to at work are about fourth dimensional beings that phase into our 3-D reality. I know I'm a weird guy I know I listen to weird stuff and entertain weird ideas but this was not in my imagination I was obviously stone sober not tired or hyped up I didn't have scratched up safety glasses on Or metal dust in my eyes there were no noises Nothing fell from the ceiling or tipped over. This wasn't a reflection off of aluminum or cast iron It's a small area it's really well lit. I was alone I didn't feel scared I didn't smell anything strange or feel off or loose track of time. No hair on the back of the neck. Or feelings of dread, I was shocked though once I realized it was not my coworker pranking me. Side note- 3 ! Yes 3 bodies have been found in the Milwaukee river in the last 2.5 years since I’ve been at this job. All 3 bodies have been found in the river that is about 2 blocks from the weld shop I work in. I am very aware of missing 411 cases and am not drawing any conclusions to those cases and what I saw in the weld shop but I do think it’s worth noting. I’ve had odd experiences happening since I was 5. I’m now in my early 50”s. Regardless I'll definitely ramp up the salt and some positive affirmations