Favoritos de davemmdave

Relatively uncommon along the pedestrian tracks of the lower cliff zone ,although it must be said that generally this location has fewer grasses of exotic and native species than I would have expected, and is dominated by herbaceous weeds mainly Gazania, plus a smattering of very tough low hardgrown woody perennials including Atriplex species, Barrier saltbush, stunted boxthorn (African) and so on .

Subject=the semi-translucent gel-like coating on much of the fucoid brown algae.
Depth ~ 40 cm. Alongside jetty,tide fairly low.
I don't know where to start,WRT phylum or etc(!?),but can think of anything from cnidaria to molluscan eggs to one of the simplest marine algae or cyanobacteria or...blah...

Unusual 4-armed morph of this 5-armed species. Found in typical position on open sandy substrate.Snorkel,depth here ~2.5-3 m.Most of the immediate surrounds consisted of low profile rock reef ,fields of brown algae(mostly Scaberia agardhii) and sea-grass meadows (Posidonia and Amphibolis and a few lush,bright areas of Zostera-like 'eel-grass,but we weren't certain if those were indeed Zostera),with a few patches of moderately large rocks and boulders closer to shore. There were relatively few small areas of clean bare sand like in the above pics, in the limited area of rocky coastline we covered on this snorkel)

Not sure who started this fight, but the pistol shrimp definitely lost it and ended up as lunch for the wrasse.

Shrimp predation is recorded as observation 144661419.

Image 1 is essentially as found, protruding from sand in a mildly raised area of the inland aspect of the swale in the Normanville North Dunes.
Images 2-4 are to assist taxon ID via viewing from different angles.

*The final 2 images are included because for me the location of this long dead valve (and I saw no evidence of its being part of a midden) tells one of 2 possible stories.
Perhaps it really was from an aboriginal midden (certainly the dunes swale had many and some remain relatively intact but others have been destroyed or spread widely by European settlement activities eg grazing, sandmining).Or, and I think this is more likely, the oyster valve was discarded by early settlers. Further information as follows.
Image 5 is taken with me standing exactly where I found it (cf Image 1) and I am facing roughly due west (actually closer to wnw).Image 6 is as for Image 5 but I am facing roughly due east. In the lower background you can just make out the leaves of the stunted cultivated fig tree which was planted more than a century ago on the inland side of the crest of the secondary dune by early Europeans. This is known to be a planted (not selfset) exotic edible fig because #1 it is apparently the only such fig tree in the Northern Normanville dunes #2 it is within metres of the now killed massive old olive trees(the huge stumps remain at ground level following decades of cutting swabbing drilling and filling) that were also planted, in the rear aspect of the dunes, on each side of the underground Morse code cable. That traversed the dunes at this exact location, before running under the beach then across GSV to Kingscote KI(laid circa late 1860s or 1870s).It served as communication between Normanville police station(at the time Normanville was the SW Fleurieu's relay outpost from Adelaide CBD) and Kingscote ,initially primarily for early alerting about shipwrecks off KI so help could be sent from eg Port Adelaide .
So, my point is that the men who manned the small hut in the rear of the dunes to maintain the cable's function and possibly also look for ships at risk of being wrecked in Yankalilla Bay during onshore gales may have collected some oysters to eat, or maybe just as fertiliser for the fruit trees they'd planted.
It is known(as I understand, anyway) that the inshore shellfish reefs of parts of Yankalilla Bay were harvested thus destroyed by dredging in a similar manner to virtually all similar shellfish reefs in southern Australia.
I'm not up to speed on what were the main shellfish eaten by the Kaurna here so I don't know if Ostrea angasi is commonly found in Kaurna middens in Yankalilla Bay (obviously at Goolwa pipi were a major component but pipi don't occur naturally here in Yankalilla Bay).
Usual apologies for the length of the above comments.

At centre of image 1.
A few seen this dive under the old Jetty.
In both images but more clearly in image 2 can be seen a juvenile Blackspotted Wrasse slightly to L of and below the subject sharpnose weed whiting.
I think the wrasse is probably hosting the weed whiting client, because the weed whiting lingered at this spot for surprisingly long time, and even seems to have adopted client pose.
Juvenile Blackspotted Wrasse are well known facultative cleaning hosts, but I have generally assumed their clients would be bigger than them. I have never witnessed any Sharpnose Weed Whiting being cleaned-by WCCs or any other known hosts, although I've seen Sharpnose WWs on other dives at Rapid Bay that were behaving in similar fashion to the above,making me suspect that they were in client mode.
So, while the above does not prove that juvenile Blackspotted Wrasse clean Sharpnose Weed Whiting, I am increasingly sure they do.