Other Conference Call Highlights:

Lester Holt on which origin theory of the crystal skulls is most convincing:

"Well, if I had to take a guess - and don’t take this to the bank - I would buy into the Mayan story. But having said that, and this is an important caveat, to me there’s not enough evidence to really walk away and say this is what I believe. To answer to your question of the potential theories out there, of the Mayan story that Anna Mitchell-Hedges tells is perhaps the most likely, assuming it was made by humans. It would require obviously a great amount of patience over a great amount of time. Obviously, too, a fair amount of skill since they would not have had the machinery to do it the way we would do today."

Holt on the most fascinating aspect of his Crystal Skull adventure:

"Well, I think it was standing amid the Mayan ruin. I’d never been to Belize and didn’t know that there were so many. And I didn’t realize that there were so many unanswered questions about them. One of the things that we do in this documentary is [that] we take you up what looks like a mountain, but what you’re really standing on is a pyramid. It’s entirely covered in dirt and jungle foliage. A lot of these have really never been fully explored. There were countless Mayan ruins that archaeologists have not gotten to, which, of course, leaves out what else haven’t we found and what else might offer credence to the story of the legend."

On whether he's held or has seen any of the crystal skulls in person:

"No. Bill Homann, who had married Anna [Mitchell-Hedges] and is featured prominently in the documentary, brought with him a replica of the crystal skull. He had real concerns about bringing the real thing to Belize because many there think it is sacred and that it is part of Mayan culture. Frankly, he was afraid that it might be seized. So in this case, he brought a replica. I’ve never seen the real thing. I’ve read so many accounts of it. When I was approached with this documentary, I’d heard - just vaguely I knew about it and I did some reading. After I read it, I became intrigued. This sounded like something that would be fun to do, and it was."

Holt on his skepticism at the beginning:

"Oh, my skepticism meter was clicking the whole way, even from the time I got into the project. That’s what a journalist does, and there was no way I was going to even work on this unless I made sure we were going to explore all these different avenues and all the evidence that would point to this possibly being a fraud. We did that. Bill Homann who has it now - I tried to shake him. I asked him a lot of pointed questions and I came away at least with the conclusion that he’s a true believer. He’d lived with Anna Mitchell-Hedges, he knows the skull and has heard her story, has asked her many of the same questions that I asked him. And he’s a true believer. Now, that leaves the obvious question - What do I think now? I still don’t know, is the answer. But I also approach journalism from the standpoint that there are a lot of things that we don’t know and may never know. Our obligation is to ask the right questions and explore all the potential avenues. I came away feeling this is a pretty interesting mystery because there have been tests suggesting that this couldn’t have been machine made. There have been the stories of it being put up for auction. So there are a lot of different stories out there. And it was kind of fun to explore all the avenues. At the end of the day, you kind of walk away and, as I often like to do with stories, assuming if we can’t get to the bottom is to let viewers decide."

Lester Holt on the Skulls' relation to the end of the world, predicted by the Mayan calendar:

"Well, I don’t know. We went to an area where we actually walk - it’s a giant Mayan calendar and it’s made of these standing stones. You’ll see it in the story. We talk about the fact that there is this legend of the apocalypse event that would occur. That’s an area, frankly, where we’re exploring the 'what-ifs' and the possibilities, and I’d leave that to the viewer to decide. We put it out there. But that’s a hard thing to, you know, to offer conclusive evidence. I guess we’ll find out in 2012."