White dots on zoa

[Liba60]

http://imgur.com/a/ufLmx

Some of my zoas have been losing their color and staying closed mostly. There are these small white dots on them. Pictures are pretty terrible with just a phone but hopefully you can see.
Anyone hve any idea?
Thanks

 

[Tristan]

Are they spread out or clustered?

 

[Tahoe61]

For some reason Palythoa incorporate particles of sand.

https://www.reef2reef.com/threads/zoanthid-grow-related-to-sand.63432/

No worries other than those brown palys taking over your tank.