ID on this weird worm (?)

[Agathos]

Hi,

I have some weird worm, at least I think it is some kind of worm. It has a solid house, almost shaped like a pyramid, and completely black. The house is about 1 mm in each direction. It seems to be moving, or expanding, very slowly along the rock it lives on, building new house as it goes. I would guess the speed is only 1 mm/month. Some times a small tentacle can be seen extended from the tip of the pyramid.

Here's the best shot I was able to make. The tentacle can just be seen. In front of the black pyramid remnants of old pyramids, they are less dark and seem to gradually crumble away. Anyone able to tell me what this is?

 

[Salamander]

Pictures are not real clear but it could be a vermetid snail. They're stationary living in tubes attached to rock. They secrete a mucus web to fish for food in the water. Its usually obvious when you've stirred up the tank.

 

[LeslieH]

That's really interesting. It wouldn't be a vermetid because the tube would be solid & not crumble away. If you would be willing to scrape it off a close-up picture would be most helpful

 

[Agathos]

That's really interesting. It wouldn't be a vermetid because the tube would be solid & not crumble away. If you would be willing to scrape it off a close-up picture would be most helpful

I'll check and see if I have more of them, if so I might do that.