In the past few days there have been some suspected sightings of Asian Shore Crabs at beaches near Melbourne such as Ricketts Point (A marine sanctuary) and Mt Martha. The Department of Agriculture Victoria recently made a statement asking members if the community to assist in surveillance for the presence of these crabs. To my understanding the initial Mt Martha observation was made by an iNaturalist user. Thought the iNaturalist community could really help out possibly through the creation of a project to monitor Melbourne’s beaches.
I am very familiar with the Asian Crab from New York localities, and I would be happy to check anyone’s IDs of that species, although I would not know the IDs of the other crabs that people would be likely to encounter near Melbourne.
This is probably a good starting point: