This is the old male Hippo at Dublin Zoo. I think he's now dead. This old pool no longer exists either. It used to be where the elephant paddock is now.
I am not sure how this happens but I don't think its all that uncommon and doesn't seem to affect the animal detrimentally. I saw another specimen with a similarly malformed tooth at Madrid Zoo a couple of years ago and (coincidentally) in a skull in Dublin Zoo's education department.
