We wrote two opposite thingsA small bell could be impossible to see on x ray and be just enough to be blocking him from pooping and making him feel worse. Why have that doubt if you don't have to?
In my opinion a metal object is clearly visible on an x-ray, because it's a clearly shaped white spot on the image.
When a cat or dog are shot with tiny bullets, they clearly show on the x-ray, and they are 2 mm thick.