human
Mobile means its moving around, which is a good sign in general (means its probably not growing from your bladder). The most likely culprit in these scenarios is a bladder stone. The fact that its nonshadowing makes it unusual because most bladder stones have calcifications that shadow. In any case one has to go in with a camera to take a look at it and do something with it.
gpt
By "mobile" I'm not sure whether they mean like rolling all around the bladder (which in this case sounds like it would be a blood clot, not a stone), or an actual soft tissue mass that is swinging in the breeze but attached to the wall by a stalk.MDTs are used for anything complicated or unusual, not just for cancer.
Granma here, just wondering...no enemas, these days?
Enemas work great, but dont go too far up. Cleanouts from above take care of the whole problem at once.