Such fascinating, mysterious sea life...
— Gemma Wiseman - on Bunurong land, Kulin Nation (@AuraGem) January 14, 2021
I dragged the photo to Google images, but nothing seemed to match or come close...
Incredible and beautiful mystery... https://t.co/YqnDbQgvO8
UPDATE: I have now learnt that this is a Anemone Phlyctenactis tuberculosa - wandering (or swimming) sea anemone...