Need assistance with white, stringy thing

[Always42Learning]

Howdy, folks, back with another hitchhiker question.
Live rock just keeps giving!!

So, I've seen this white stringy stuff on one of my rock pieces, a good two inches long each. I never really gave it much thought until today, when I threw in some shrimp bits, and the stringy stuff grabbed one of the bits and hoisted up on the rock!?!

A bit later, some of the stringy pieces tried to wrestle a different bit away from one of my dwarf hermit crabs!

(sorry for pic quality - working with an andriod phone.)

Now, I'm guessing I don't feed my critters all that well, cuz a brittle star (I'm assuming) also grabbed some shrimp from a few hermits. I do throw a bit o' shrimp in every three days, and a bit o' dried seaweed in between, and now I have algae wafers coming to drop in on the non-shrimp days to see if that helps.

So, any idea what this white-tentacled menace is and whether or not it'll eventually come for me in my sleep? (If it matters, the rock where these tentacles reside occasionally has a volcano-like blast of gunk right out the top.)

The tank is only CUC critters: 25 dwarf hermit crabs, 15 snails, 1 peppermint shrimp, and 1, maybe 2 brittle stars hiding in the rocks.
thanks!
JJ

 

[Impala67]

Vermetidae snail

 

[corey904]

Looks like a monster vermited snail
Their a bad hitch hiker but not something that could crash a tank only bother a few corals every now and then

 

[ying yang]

Vermitted snails cast like mucus web and these are multiply tentacles with white dots in so either it's like banded or it's taking food down the tentacles like spiniod worms do but they got 2 tentacles so could it be multiples of them or some kind of worm like a spaghetti worm but not a spaghetti?
Them tentacles like what 4- 6 inches long ? Can't really make scale out

 

[corey904]

Is the critter able to move around the tank or staying in one spot

 

[keatonmjenkins]

Just super glue the top of the shell and it will get rid of it. They also spread pretty quick so you might soon start seeing smaller ones pop up.

 

[Always42Learning]

Howdy, folks, back with another hitchhiker question.
Live rock just keeps giving!!

So, I've seen this white stringy stuff on one of my rock pieces, a good two inches long each. I never really gave it much thought until today, when I threw in some shrimp bits, and the stringy stuff grabbed one of the bits and hoisted up on the rock!?!

A bit later, some of the stringy pieces tried to wrestle a different bit away from one of my dwarf hermit crabs!

(sorry for pic quality - working with an andriod phone.)

Now, I'm guessing I don't feed my critters all that well, cuz a brittle star (I'm assuming) also grabbed some shrimp from a few hermits. I do throw a bit o' shrimp in every three days, and a bit o' dried seaweed in between, and now I have algae wafers coming to drop in on the non-shrimp days to see if that helps.

So, any idea what this white-tentacled menace is and whether or not it'll eventually come for me in my sleep? (If it matters, the rock where these tentacles reside occasionally has a volcano-like blast of gunk right out the top.)

The tank is only CUC critters: 25 dwarf hermit crabs, 15 snails, 1 peppermint shrimp, and 1, maybe 2 brittle stars hiding in the rocks.
thanks!
JJ

the white doo-dads are 2-3 inches long...
they are on the same rock as this feather duster - the more active the white doo-dads are, the more the feather duster seems to close up

the feather is about 2 inches in diameter

the rock they share is fist-sized - the feather is on the right and the white tentacles come out the front, with the occasional spew coming from the top...

JJ