For many years there was a dent in the tiles on the Giraffe House wall, where a (bull?). giraffe had swung its head at a keeper. The dent was covered with glass and labelled. For some reason it's not there any more.
I remember that from when I was a small child; it disappeared about 1960 when the Giraffe House was refurbished as part of the Cotton Terraces development.
If you remember that, you probably also recall Frank Buckland's plaster cast of a hippopotamus calf that adorned the wall of the building; that also "disappeared" about the same time.