What is this?

[Dreamweefer]

I know what it is not; Duncamopsammia.
What it does, it pulls it self around on the sand using a tongue/foot.
So i thought it may be a nudibranch but google images was no luck in finding a match.

 

[Reefing Madness]

 

[Defect]

Looks like a walking dendro. Check this thread. https://www.reef2reef.com/forums/ch...king-dendros-stock-heteropsammia-cochlea.html