Need Hitchhiker ID...lives in my nightmares

[rstick1]

Hi All,

I have searched high and low through hitchhiker guides to no avail. This creature manages to look like a clam, a crab, and worm. Maybe I am overlooking something, but I need help.

This is what I know: The Thing lives in one particular hole in the rock work. I have never seen it move from this spot, but I have seen it move. If you approach it too quickly or shine a light on it, it retracts, folding into itself and pulling itself partially/completely into the hole. Like the witches legs in The Wizard of Oz. When it retracts it suddenly looks like it has two hermit crab legs.

Source of The Thing: I used caribsea life rock, which i believe doesn't have anything living besides bacteria. I am under assumption then that The Thing came from a coral.

Below I have attached two pictures and a link to a video of it moving.

The thing where it lives.

The thing retracting revealing its "legs".

Video of it retracting due to light:


Thank you all who take the time to look at this!

 

[WheatToast]

Closest thing would be a barnacle. Because of their strange appearance, they used to stump taxonomists, though we now know they are sessile crustaceans. They are harmless filter-feeders that are distinguished from feather duster/tube/fan worms by the curling motion of their legs (yes, those are its legs) which do not form the shape of a cone when extended.

 

[rstick1]

Thank you so much! This makes sense. I can see the similarity in the appearance of the legs especially in the first picture. Excited for my new bonus pet!