Urolith

This strangely beautiful sculpted object is actually a bladder "stone." The coin in the background is a one pence piece.

In some people and animals bladder stones form from proteins and the minerals in the urine binding together and crystallising into to a dense mass which cannot be voided. These stones are more common in certain breeds of dog and on certain diets, they are also much more common in animals which drink sparingly compared with those that take in a lot of liquid. If your dog develops a bladder stone ("urolith") it might cause pain during urination or bleeding into the urine. Less commonly the urolith can completely obstruct the urethra (the tube leading out of the bladder). If that happens complete urinary obstruction quickly becomes a very painful problem and then a life-threatening crisis as the body can no longer excrete wastes. Of these "wastes" the most acutely toxic are potassium and acid (K+ and H+); retention of these ions can kill in as little as 12 hours.

The elderly dog who harboured this stone is now recovering under the benign analgesic umbrella of some methadone.