Just cos I wanna post my cool piccy again...
Doesn't mean anything just something to get your imagination going...
https://drive.google.com/uc?view=export&id=0B8ck-2ELKOuLalBFYTQ0WHRBUGs
I do find it odd that an alien civilisation would "mark" their stuff with a symbol, it only seems to make sense where multiple "symbols" are competing and to indicate ownership. I mean clearly the barnacle belongs the the aliens, it almost implies subgroups of aliens. And as such (although I don't necessarily think it's likely), barnacles with alternate symbols is a possibility.
Doesn't make much sense I know but why else stick an "ownership" symbol on something, unless there's some notion of "competition".
ahem ....

Hey MB all your Barnacles are ours !!!!