Summary: Biphosphammite, ammonian KH₂PO₄, syngenite, aphthitalite, monetite, hannayite, whitloekite, apatite and minor gypsum, taylorite, brushite, mirabilite, guanine, and unidentified compounds form crystalline crusts on the walls and floors of a chamber of Murra-el-elevyn Cave, Cocklebiddy, Nullarbor Plain, Western Australia. The minerals are derived from the interaction of bat urine, droppings, and limestone. Analyses for CaO, MgO, Na₂O, K₂O, SO₃, P₂O₅, CO₂, NH₃, H₂O^-, total N, and ignition loss are given. High K₂O and low total N figures are characteristic of the analyses.