While walking along a Darwin (Northern Territory, Australia) beach at low tide, it is possible to find a small treasure in the form of a fossil. They are the cast off shells of the Mudlobster (Thalassina squamifera), a type of crustacean that lives in 2 metre deep, complex burrows in the mud. Their shells are gradually encased in a mudball and then become fossilised over time. It is estimated that most of the fossilised Mudlobster specimens near Darwin are up to 7,500 years old.