What are these white spots on my Astrea Snail?

[poppafish]

What are these white spots on my Astrea Snail?

 

[monkeyCmonkeyDo]

Spinoids. Tiny feather dusters.

 

[poppafish]

Spinoids. Tiny feather dusters.

are they dangerous?

 

[ISpeakForTheSeas]

Spirobid worms - harmless filter feeders.

 

[Cali Reef Life]

Extremally Dangerous for anyone within 6 feet of the tank. Just kidding harmless unless you get one under your algae scrapper and scratch glass.