Is this a pest?

[tygger]

Can't tell what that white thing is in the center. Any ideas? Thanks

[AlSimmons]

Are you sure they're not grains of sand? You might want to use a stick or something and see if you can brush them off.

[tygger]

Yep, I tried and it seems attached... is it normal for substrate to attached to the top?

[hecterma]

Could it be zoanthid fungus?

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[ozmosis7]

Looks like it got burned by something to me.