Snails have white bumps

[New&no clue]

I notice some of my snails have white bumps all over their shells, is this normal or sign of a problem?

 

[Crabs McJones]

They look like spiroribid worms

 

[eggplantparrot]

^ not a problem to the snails but it can overtake your tank if you feed wildly. they are filterfeeders.