So to summarize my thoughts, it seems there are a couple of Nebulae that have to do with the origins of the barnacles. The first nebula was discovered because the UA’s around that area pointed to center of that nebula which was the system MEROPE.
The symbol on those barnacles appears to look like one nebula but MB confirms that there is more than one nebula connected to this whole puzzle. I suspect that symbol is a combination of 3 nebulae. The symbol is formed of 3 different shapes and I think these are three separate nebulae.
I strongly think now that the UA’s are pointing to the center of their bubble or shell where they are found. To confirm this, I suggest those in the California nebula who have found barnacles that they explore the outsides of that nebula in search for UA that are probably forming a shell around that nebula. Then see if they point to the center of the califonia nebula. If my theory is correct we have found 2 of the 3 nebula depicted in the Barnacle symbol. Using the three nebulae as a point in a triangle I suspect that it can be used to triangulate the center of these 3 nebula to find something in the exact center.
This is also good thinking, but I don't think that there is another UA shell. Here are my reasons:
All UAs point to Merope. This started wit the release of 1.4 (beta to be precise). I was there when Ratking15 took the first ever UA to Merope for testing.
All the early testing were done on UAs that were not found in the Shell. Ratking's was liberated from a convoy, others were found in SSS in the Pleiades and some were even duplicates from the instancing bug.
As a game object, all UAs are the same. They are cargo canisters. There is nothing suggesting that the object knows where it was spawned. In fact, it probably re-spawns when jettisoned. I doubt that the object exists while we have it in the cargo hold. They have never shown any indication to be persistent.
This means that to have a second shell, the game would need a second UA object. UAs in the new shell will have to be of a different type, that point to a different place. This is of course as very small task for the devs to make a copy object with a few changed properties, so it's not impossible.
If we are to believe the Wings trailer, the first UAs were found in the California Nebula or beyond. They still started to point to Merope, when 1.4 dropped.