Hard white deposits

[NedFlounders]

I’m sure this is pretty common but I’m not sure what it is. The dark blue pic is of these things in the display. The well-lit picture is in the sump. They are somewhat hard like a calcium deposit but seem brittle and break off when I wipe them off. I’ve never seen anything emerging from them like vermetid worms...any ideas?

https://drive.google.com/file/d/1goRcuTH11ShC7ddESHtKvnEkkZDGA9Ap/view?usp=drivesdk

https://drive.google.com/file/d/1KAMPSXwF0hyJfaw9tqBfVc71mqRSeIE1/view?usp=drivesdk

 

[Rafty]

Images broken


Sent from my iPhone using Tapatalk

 

[NedFlounders]

Had to use direct links but they should work now.

 

[Four drachma]

Spirobid worms...


Sent from my iPhone using Tapatalk

 

[NedFlounders]

I thought too but they aren’t spiral...

 

[Vinny Kreyling]

Harmless filter feeders.