An introduction to Invertebrates:
https://australianmuseum.net.au/learn/teachers/learning/what-are-invertebrates/
Marine invertebrates are included in their own category.
Australoplana alba at Flynn, ACT
Richardsonianus australis at Murrumbateman, NSW
Richardsonianus australis at Murrumbateman, NSW
Oxyloma elegans at Campbell, ACT