Cucumis myriocarpus Paddy Melons
A native of South Africa, this is a roadside weed in Western Australia. The leaves and fruit contain a toxin and so is an unwelcome alien where livestock are kept. It is a a member of the Cucumber family (Cucurbitaceae). In this photo only the fruit, which are also known as Prickly Paddy Melons or Gooseberry Gourd in the United States, are shown.
The pink flowers are Schoenia cassiniana (Pink Everlasting).