acro polyps????

[jjv123]

Anyone know if these polyps look normal? I have other acros that do not have these extensions. Mainly at night time a normal looking polyp emerges. This is a new piece for me. Not sure of species. It's blue. I wonder if these are some type of parasite? I dipped, and they did not fall off.

 

[saltyfilmfolks]

Those are hydroids. They'll usually go away..
http://www.lionfishlair.com/hitchhikers-guide/

 

[jjv123]

Will these hydroids spread to non acropora corals, or other substrates for that matter?