Image of buoy barnacle

Description:

I have a sneaking feeling I've seen an observation of one of these before, but I've certainly not observed one before. I have not a clue as to what it is, unless it is triffid spawn ;-) It has a transparent base with concentric rings and even a central (though very transparent) sail/wing like a by-the-wind sailor, but then a stalk with a head on the end like some tunicates or goose barnacles. Out of that head is a waving set of legs? that propel it about a bit, maybe collect food. It seems as though there is a separate animal in there operating these legs. Very interesting beast :-)