When I was a kid (not positive on age, I’d guess around 6 or 7), I was playing with toys by myself in our families living room. I clearly remember seeing a light grey shape on the floor near the window in the sun. Thinking it was our dog who was a large fluffy grey critter, I played contentedly for quite some time while the shape hung out nearby. Only when I heard our dog barking in the backyard did I look directly at the shape. I don’t remember it having any discernible features, it was a misty light grey cloud type shape around the size of a large dog or small person. Low to the ground like a dog or cross legged sitting person. You could see through it to the floor and wall behind it. I didn’t look too hard at it because as soon as I realized it wasn’t my dog I ran downstairs to find my mom. By the time we came back upstairs it was gone. I remember being freaked out because it surprised me and I didn’t have an explanation for it, but I also remember it not feeling ominous or at all “scary” if that makes sense. I never told anyone about it because I assumed no one would believe me. As a kid I always thought it was the ghost of our older dog who’d died a few years before, but as an adult I’m not sure. The house was built in the early 1900s, lots of beings could have existed there over that time. All I know is I’ve never seen anything remotely like it in the 30 years since. I’ll remember it for the rest of my life I’m sure.