Looks like giant hydroid but acts like sessile worm

[cocoReefer]

Ive had these for many years now in my refugium mud. Never in the display (must get eaten) i figure they ambush pods. When i dig them out they cant swim or move well. About an inch to 2 inches total length, with 80% stuck straight in the mud

Look like a feather duster that watched the movie “Tremors” too much.
Not worried about them, but have never found what they are.
My tank is in the 10-15 yr range and 90% live rock from back when.
Any ideas?

 

[cocoReefer]

Tried to suck one out for a full frontal nudie, but it slipped down too deep.
No tube, whole body goes into the mud very fast.
when i harvest my overgrown cheato i will try for a video, or get gumption to dig one out.

 

[Tired]

If you put a mysis shrimp or something on them, do they eat it?

You say they can't swim well. Do they swim at all, if dug out? Do anything other than sit there like an anemone?

They're pretty cool-looking. The transparent tentacles make me think cnidarian of some sort, because worm appendages usually seem to have more color.

 

[cocoReefer]

If you put a mysis shrimp or something on them, do they eat it?

You say they can't swim well. Do they swim at all, if dug out? Do anything other than sit there like an anemone?

They're pretty cool-looking. The transparent tentacles make me think cnidarian of some sort, because worm appendages usually seem to have more color.

Ill do that in when i feed tonight, see what happens. Got loads of all sorts of pods and dont see the ????? Reproducing fast, but always have some.
id agree they do seem very cnidarian. Basically no swimming. Kinda curl the tail end. Probably the function they use to retract into the mud.
I worked in a lfs 15 years ago and had a habit of taking everything home to my reef. Mud under coral racks and whatever i could find in the sumps, along with tons of live rock, sometimes fresh and uncured. Looking back now im very lucky i never grabbed more pests. Only ever had some manjano anemones way back when.

 

[Tired]

Looks like you've got a great variety of cool stuff in there. Besides all the labeled critters, I see acoel flatworms. I know some people don't like those, but I think they're neat. Any pics of the whole 'fuge?

You could probably seed some tanks really nicely with a handful of mud from in there. Must be all sorts of biodiversity, and proven to do well in reefs at this point!

I don't know what the funky guys are, but I'd imagine if they were worms, they'd be much more vigorous when provoked. Maybe they're some sort of long anemone. Have you ever seen any that were budding?

 

[cocoReefer]

Looks like you've got a great variety of cool stuff in there. Besides all the labeled critters, I see acoel flatworms. I know some people don't like those, but I think they're neat. Any pics of the whole 'fuge?

You could probably seed some tanks really nicely with a handful of mud from in there. Must be all sorts of biodiversity, and proven to do well in reefs at this point!

I don't know what the funky guys are, but I'd imagine if they were worms, they'd be much more vigorous when provoked. Maybe they're some sort of long anemone. Have you ever seen any that were budding?

I havent seen them budding. Some are very large and others smaller. They seem to space themselves pretty well, and no clusters/colonies.
Just fed one and the “tentacles” do move independently of each other. It didnt close like a mouse trap, but rather let food fall and felt around for it. Then tipped its mouth toward a piece and swallowed it.
Ill take photos of the refugium but its got 10 gallons of cheato covering anything cool at this point. Need to harvest.

 

[cocoReefer]

Looks like you've got a great variety of cool stuff in there. Besides all the labeled critters, I see acoel flatworms. I know some people don't like those, but I think they're neat. Any pics of the whole 'fuge?

You could probably seed some tanks really nicely with a handful of mud from in there. Must be all sorts of biodiversity, and proven to do well in reefs at this point!

I don't know what the funky guys are, but I'd imagine if they were worms, they'd be much more vigorous when provoked. Maybe they're some sort of long anemone. Have you ever seen any that were budding?

Thanks. Its a 40 breeder i setup as a sump 10 or more years ago. Lots of different sponges, bugs and algae. Ive seen bacteria eat piles of detritus in there even. Its been a great fuge. 2 pencil urchins that are also about 10 yrs old, and a cucumber thats bigger than i ever thought it would get. The urchins eat anything, but dont seem to get the critters in question.
Just bought a fresh 40 and getting glass cut to redo the setup. Need to put it lower to add a 20 long for frags.
I have seeded a couple tanks recently.

 

[cocoReefer]

Well....
I did find them in my display. Did some late night sand searching. ( dont comment on the ugly dsb, im aware and its my tank. i like it deep and ugly )

About a quarter the size of the ones i see in the refugium mud. Can see some of the body against the glass. White near the mouth that sits above the substrate and a striped tube going downward. Photo is zoomed in and magnified. Its near a mm diameter.

They are in clusters and do seem like they could be “budding”. There is a cluster of 3 there, and the “feet” all angle to each other and appear to be touching about an inch under the surface. Sorry the photo quality isnt that great, but again its zoomed in and then magnified.
Looks like they have radial symmetry and are not segmented like annelida.
FYI this is the dirtiest corner and the deepest section of sandbed.... nearing 6-7 inches. Where my bristle tooth has been hiding sandy poops for about a decade....literally inches of excreted sand here in this quiet bathroom corner....

 

[cocoReefer]

This one started to slip away, but a good long view of the main body against the glass. The vertical stripes look to correspond to the tentacles ( tentacles retracted on this one as its pulling itself under the substrate )