Located east of the wheat-belt town of Hyden, Wave Rock is a 15-metre-high, 100-metre-long granite cliff, weathered into the shape of a wave over a period of 2.7 billion years. The vertical bands of colour on Wave Rock that appear like kelp coming up through the water are caused by streaks of algae. Nearby is Hippos Yawn, another outcrop of rock shaped like a cavernous mouth; The Humps, which are camel-like humps of granite; and Mulkas Cave, where a feared Aboriginal spirit named Mulka lived. His handprints can be seen on the walls. Gnamma holes are another feature of the landscape – small soaks in the rock where Aboriginal people collected water.