The problem is that there are lots of logical reasons why the barnacles might be in nebulae. It's very easy to go from knowing the answer back to the clues, but not so easy following the clues to the answer. A quick list of some properties of nebulae:
- They contain younger stars
- They contain a higher density of free-floating elements
- They are easily recognisable at large distances compared to individual stars
- The dust makes it harder to find things inside them
- They are more attractive to human explorers, especially the novice ones
- They feature relatively prominently in human mythology
And I'm sure that there are many more. When we know the answer as to why the barnacles are where they are we'll be able to go "yeah it's obvious now", but working forwards with so little information is a very difficult thing to do.
I'm also thinking that this is a most importent clue that we ever had.
It means that nebulease have something that the other part of the space don't. I't free floating gas.
If those Barnacles are similar to Earth ones then theare are filtering the elements that they need form the space. But what we know about forming the new star, is that in the system who actually have one there in no more frre floating gas becouse it was used to create the star and the planets. So i think the Barnacles would be in forming star system. That would be a T Tauri star system.
Also I was thinking about the magnetic field effect of the planets. The big planet with active volcanism got a magnetic field wich can shield the planet from the gas in space. Also moons orbiting the gas giants can be shielded by they magnetic field.
So, I would be searching in the T Tauri systems inside the nebuleae on planets without volcanism. I thonk it shouldn't be Ice planet (Earth Barnacles grow on solid surface). And i still think that the mist will be the indicator of the right searching place.