It's definitely a chiton. There are 150 species of chiton in Australia, and 80 of those are endemic. Here's a guide to chitons in the Port Philip Bay area: http://portphillipmarinelife.net.au/search?searchType=Identify&searchText=5
The skin around the outside looks similar to my spotting:
http://www.projectnoah.org/spottings/8177277
Mine was found in New Zealand but there is an Australian version with a different scientific name.
Comments (5)