what are these?

[reef tank 2.0]

Over the past nmonth or two, I've noticed these white looking "things" all over my rock. It's only on the rocks. They never move, they never "hatch" (i don't think), and they never go away. I haven't tried wiping them off. They don't go away when i try to blow them off either. Like I said, they are all over my rock throughout the DT.

Heres a picture of them. Do not focus on the calcium deposits on the back glass, the white things in question are in the foreground . they almost look like mini cacoons

 

[Misled]

Scypha or Pineapple sponges.

 

[reef tank 2.0]

uhhhh, where did they come from, what purpose do they serve? will they eventually go away?
my tank has been running for 8 months now.....

 

[SeaCucumberFan]

They come as hitch hikers on live rock. They're great filter feeders. Keep em