Trypaea australiensis, known as the (marine) yabby or ghost nipper in Australia, or as the one-arm bandit due to their occasional abnormally large arm,[1] and as the Australian ghost shrimp elsewhere,[2] is a common species of mud shrimp in south-eastern Australia,[2] and may be the only extant species in the genus Trypaea.[3][4] T. australiensis is a popular bait used live or frozen by Australians targeting a range of species.[5] It grows to a length of 6 centimetres (2.4 in) and lives in burrows in mudflats or sandbanks, especially in or near estuaries.[6]