They look like shells, but are actually a bit flexible, and very soft and smooth inside:
They're what remains of very curious creatures known as cunjavoi (Pyura Stolonifera), a type of sea squirt:
The Cunjevoi is a sea squirt found around the edge of the low-tide mark that often forms mats over the rocks. It is sometimes covered in green or brown algae and has a tough brown exterior or 'tunic'. During high tide, the Cunjevoi feeds on plankton as water is pumped in and out of its siphons. As the tide recedes, it holds water to keep from drying out and, like all sea squirts, squirts a jet of water like a water pistol when squeezed or trodden on at low tide.
They're normally very rough-loooking, but we're seeing cunjavoi that have been scooped:
Cunjevoi is an Aboriginal name and the animals were once a common food source for Sydney's Aboriginal people. Today, the Cunjevoi is popularly used as fishing bait. People cut the Cunjevoi, scoop out its soft insides and leave the hard tunic attached to the rock. However, the Cunjevoi is a protected species in some parts (marine reserves) of Sydney Harbour.
Their most bizarre characteristic, at least in my opinion, is that in the early stage of their life, they're free-swimming:
After spending their larval stage as a free swimming tadpole like larvae, with a distinctive nerve chord, adult animals are filter feeders that live permanently attached to the lower section of rocky shores.
But I was there to do some work—some fishing work. My first ever cast in Australia:
This made for a happy Thom (with an Aussie flag in the background):
Christine snapped some more fishing shots:
Christine took a shot of our pretty little street:
Soon we'll get some snorkeling shots. Soon: