I'm from south-west Australia (where these dolphins were observed) and grew up swimming along the coast, scuba and snorkelling to much delight.
Once, in a little sand hole near Yanchep, I was floating around on a particularly hot day, when I thought I saw a crayfish just lolling around on the ocean floor. Diving deeper to get a closer look, I realised it was just the head of the crayfish, long-since hollowed out, albeit with a bit of flesh still onboard.
I took an even closer look, and what I thought was a bit of weed attached to it was actually a long, slender tentacle, which I followed back to a minuscule hole in the rocky sand, and therein I spotted the rest of the octopus.
Delighted, I stuck around for a while to watch.
The octopus was fishing! It held out the cray corpse just a little, out in the currents, waiting patiently for the stupid little white fish to come and try to nail a bite!
When a particularly dumb little fish got its fangs in, BAM! Out came another tentacle, fast as light, and snatched that dumb fish into the hole. All the while, the original bait tentacle continued to just lull about, swinging and swaying, getting those dumb fish even closer and closer, ever more tantalising.
I stayed and watched it all day - it apparently had a nearly-insatiable hunger, or maybe it was just really enjoying itself. To my dying days, I'll never forget that clever little cephalopod ..