As promised, here's the sessile Vagorus specimen I found...
Originally, I mistakenly thought this thing was a gigantic Drifter zooid stuck to a piece of the environment. However, upon closer inspection, it turned out to be a Vagorus specimen with a magnificent morphology!
Named the Quill (based on its similarity in appearance to its namesake), this strange specimen has given up its nomadic lifestyle for something akin to filter feeding:
As you can see in the above illustrated diagram, the Quill anchors itself on the various pieces of detritus found in the Vagorus nesting environment, usually on singular pieces of rock/dead organic matter that are nearby or in the way of a constant current of water. It lies there, waiting for unsuspecting prey to be swept by said current and into the feather-like feeding structure, where it uses a whole array of organic weapons to ensure quick incapacitation and absorption. Meanwhile, the "holdfast" of the creature is itself heavily armored and protected, preventing any sneaky creatures from trying to ambush and dislodge the Quill.
Overnight observation by automatic recording equipment of the specimen also reveals a stunning adaptation:
Apparently, when the Quill deems its current anchoring spot unsustainable (by, and I'm really making a huge assumption here, somehow measuring the amount of prey successfully caught and eaten relative to time), it can un-grow its holdfast and assume the above form (that I dubbed the "locomotive form"). As such, it is able to completely relocate itself should it desire to! However, the "locomotive form" has some glaring issues, particularly in anti-flanking (the rear has no defences now!).
Welp, that's all for now, I'll continue to keep y'all posted if I discover anything remarkable.