Actually . . . now that you bring up that ancient tidbit, that little utterance makes a lot more sense! I figure there's some matter of familial relation between the Giant and Mike wherein the creation of Laura's spirit or energy bears familiarity and by succession, the Arm as well. Very interesting point!
Bob is Mike's familiar. That doesn't necessarily mean they're related. In the 40 years that Bob existed, he must have in some way worked his "charm" on Mike and convinced him to work in contingent for the pursuit of chaos. However Mike had a reckoning and removed his Arm as sacrifice and penance. I get the feeling that Mike's existence is much longer than Bob's.
Is it possible that the Giant/Fireman created more than one gold sphere? We see him levitate and create a golden cloud that produces a golden sphere. The focus is on the long sequence that shows the sphere descend to Dido who sees Laura's face and sends it to Earth.
But, there is also a wide shot at the end of that sequence that shows the Giant still levitating with the golden cloud still looking very active.
I'm sure it is irrelevant to The Return, but from a broader mythical standpoint it could suggest there were other spheres created and sent to Earth.
She could be a weapon, a cure, some bait, some anti-radioactive material, a victim for Bob, a wife for Bob (if this is not Laura but some new entity), the concept for a tv show, a metaphor of Twin Peaks merchandising, a new business card for whoever took that photo, hell it could just be a copy of the photo itself in some cheesey bargain basement goldben orb photoframe.
They give us no information what it means so we will never be able to work it out - it's the most annoying thing about the whole season! Like they decided to deliberately with-hold it on purpose, for no better reason than making it difficult for us. Abstraction through omission to make something purposefully obtuse doesn't feel like true abstraction to me : (
I am sure Lynch & Frost know the answer, even if it is simply "It just came to me in a daydream while I was sitting in my chair having a smoke". In fact I will assume that is the answer from now on: "Ah, it's nothing. Just something Lynch pulled from the unified field while he was having a smoke."