[lupusreal]

Things that look like snakes like those weird mimic moths or a coiled garden hose in tall grass can also trigger that uncanny feeling to me. I suspect serpent recognition is coded into many animals at a very deep level, and anything that trips that recognition will seem uncanny.

[tanseydavid]

If you have cats you can trigger this response with many of them, using a leather belt.

If you hold the belt at the buckle end and then lay it on the floor while rotating your wrist back and forth, the belt will writhe and curl in the manner of a snake.

Many/most cats will instantly respond to this and they will try to strike the belt while simultaneously keeping as much distance as they can -- but still compelled to keep trying to strike the threat.

[hobs]

Affective Blindsight detection of snakes is real and supports that at least the primates have that; there's plenty other animals that freak out at snake like objects (cats, elephants, etc)