What is this white fuzz?

[Holy handgrenade]

Any idea what this is? I only found it on one spot on my rock and some on a coral frag plug

 

[Goaway]

Could be snail fur - hydrac echanata manual removal. I never had it, cant say if it will die off or become invasive.

 

[vetteguy53081]

Looks like colonial hydrozoa (Turritopsis dohrnii ) especially with presence of droid head as shown below:

 

[Holy handgrenade]

Looks like colonial hydrozoa (Turritopsis dohrnii ) especially with presence of droid head as shown below:

Should i be worried about it spreading or harming coral?

 

[vetteguy53081]

Should i be worried about it spreading or harming coral?

They are capable of stinging nearby coral ( a sting that irritates, not kills coral)
Snip of at the base of each strand and scrub off remainder (preferably outside of tank in container of tank water)