I thought it was a snake. Crept up as quietly as I could to get a pic, and I was so pleased with my stealth (the snake didn't move, so I must have been very, very quiet).
For years I've kept a rubber snake in my vegetable garden, because I was told that it would scare away squirrels. (Note: nothing scares away squirrels). Every time I walked through the garden, there was a nanosecond when I thought that rubber snake was real.
The trouble with human perception is that it often causes us to see what we expect to see, and that inevitably causes us to mis-perceive what is really there. More than once I've seen a real snake nearby and thought it a stick or a rubber snake or some other harmless object.
Mistaking a real snake for a stick might be dangerous. Mistaking an innocent stick for a real snake could be worse. Fighting straw enemies is exhausting.