White things on my snails????

[mcbdz]

Can anyone tell me what this is on my snail shells. Could it be some type of barnical? Good or bad?

possible on this kinda shell too

and see lots at the bottom of this euphillia skeleton below the head?

 

[Alexopora]

I was going to say spirorbid worms but upon closer look they seem to resemble Nerite snail eggs. I used to have a Nerite snail (Zebra nerite, commonly sold as a Fw but is more of a brackish) that was ina tank that transitioned from FW to salt. And that nerite lived in that tank for ab a year, laying eggs all over the glass, other snails and rockwork.

 

[Soren]

+1 Nerite snail eggs. I have them all over my tank (mostly on the back wall) from my 5-10 nerite snails.
In your first picture, you can see some that have hatched while most have not hatched yet. Also, I think the snail in the first picture with the white spots may even be a nerite snail!