A little more than 6 miles off the coast of Point Dume in Malibu, California, an unusual-looking structure sits on the sea bed floor. Based on images obtained on Google Earth, the oval-shaped object has a huge flat top and what appear to be pillars or columns that seem to reveal the entrance to a darker, inner place.

The anomaly -- for the moment, we'll call it that -- is approximately 2,000 feet below the surface of the water, measuring nearly 3 miles wide. What exactly is this thing?

According to the website of a California-based radio program, "Fade to Black," this may be "the Holy Grail of UFO/USO [unidentified submerged objects]" that researchers have been looking for over the last 40 years.

Watch this video created by "Fade to Black" radio host Jimmy Church about the Malibu underwater anomaly.

Jimmy Church, who hosts "Fade to Black" on the Dark Matter Radio Network, told The Huffington Post one of his listeners -- someone named Maxwell -- contacted him last month with a Google Earth image showing something odd, underwater off the coast of Malibu. Church then asked graphic designer Dale Romero to capture as many angled images of the anomaly as he could.

"I needed him to find a way to get it under and above the water," Church said. "My first impression was that it was Greek, it looked artificial and didn't look natural.

"When you're looking at it from above, it's a nearly perfect oval shape," Church continued. "In the natural surroundings, nothing is symmetrical. Everything is eroded and covered in rocks and sloping and peaking, and right here, for 2 miles, it is a perfect oval with a black separation or outline to it.

"It just stands out that it has to be some type of roof. It's not unlike a domed stadium or a covered indoor race track or an Olympic arena -- it's got that feel to it. It looks like a perfect oval manmade structure sitting on a construction site."

Using the Google Earth coordinates -- which are, by the way, 34° 1’23.31″N 118° 59’45.64″W -- Church and Romero came up with a series of images, starting from due south, looking north, all the way around and ending up at due north, looking back south.

Check out this Google Earth slideshow of the alleged Malibu Anomaly.

As unusual as this "anomaly" appears, is alien-UFO base the only realistic explanation for it?

"I didn't see anything special about it. I think it's because it looks like there's a flat surface and then, below it, it looks like there are these vertical columns, so somebody can say, 'Oh, this is the entryway to something special,'" said earthquake geologist David Schwartz of the U.S. Geological Survey.

"I think it's natural and is a part of the continental shelf," Schwartz told HuffPost. "It's just a complicated part of what's now offshore that has seen some erosion and, maybe, slumping when perhaps this was partially exposed when sea level was lower. This is a really major earthquake area and perhaps some of these features are a result of slope failures, due to shaking.

"There's no flag under the water that says: 'I'm the entrance to an alien base.' There's nothing unnatural-looking about it -- it's just showing some sort of variation in the offshore coastal morphology," Schwartz said.

Schwartz shared with HuffPost a research paper published in 2009 by the Geological Society of America, showing cross-sections of the anomaly area -- designated as Sycamore Knoll -- by those who actually studied this underwater region.

The following image is from that paper. If you look to the left of the middle of the illustration, you can clearly see the oval-shaped "anomaly" some refer to as an underwater UFO base:

"This is interpreted as a thrust fault," Schwartz said, "meaning one side of the crust moves up over the other -- and what we're looking at is interpreted as being the surface expression of this Dume thrust, which is part of a large fault system in Southern California."

The bottom line, he added, "is that people have recognized this."

Could that be the final truth of what this object is?

HuffPost reached out to John Anthony West, an independent Egyptologist, who won an Emmy award for his research for the 1993 NBC documentary, "Mystery of the Sphinx," in which he and geologist Robert Schoch presented evidence that the Great Sphinx of Giza may be thousands of years older than previously thought.

West examined the images of the Malibu underwater object.

"The pictures are a bit misleading in that it looks as though it's on the shore," West told HuffPost. "My first reaction -- knowing that it was 2,000 feet under the water -- was that, under no circumstances could it, in fact, be artificial, manmade. And I have enough experience, looking at geology and distinguishing between what could perhaps be artificial, and then there's sort of a gray area in-between. As far as I'm concerned, there's no gray area."

West says he's inclined to go along with the geological explanation.

"It doesn't look at all manmade. It has what look like pillars there, but they're unevenly spaced and then, to the right, you see other seemingly pillars still attached, actually, to the bedrock, in the process of forming."

And yet, West acknowledges Unidentified Flying Objects.

"I'm convinced that UFOs are a reality -- there's too much evidence out there. Beyond that, we don't know anything. We don't know who they are, why they're here, [or] how much of this stuff is our own government. A point beyond that is that anything that isn't explained or that can't be explained by current scientific methods, automatically it's aliens. It's the explanation of last resort, and I just don't buy that."

Also weighing in on the Malibu mystery is former FBI Special Agent Ben Hansen, who has an extensive background investigating and analyzing questionable pictures and videos.

Hansen supplied HuffPost with the following Google Earth image of the underwater object in question:

"This was taken from a different angle of the 'mysterious base,'" Hansen told HuffPost in an email. "The dark areas that people are saying look like the inside of the base really starts to look just like shading of indentations to the shelf, and the 'pillars' are now represented as jagged ridges."

Hansen cautions about how we interpret things we see on Google Earth.

"Google obtains their underwater data from several different sources, including satellite radar and echo sonar from the Navy, NOAA, NASA and other agencies. Because they often use very different technologies, the derived information isn't always going to agree. When it doesn't, Google relies on its automatic 3D auto-generation programs to make sense of it.

"We're dealing with limited information to render the graphic because we can see it evidenced in the disparity of image quality between the anomaly and the areas immediately surrounding it," Hansen added. "The blurry sections and jagged edges obviously suggest a patchwork of image processing has taken place."

In the end, we're left with a variety of theories to explain the Malibu anomaly, a.k.a. Sycamore Knoll. Will the UFO-alien-underwater-base proponents be eventually proven right, leaving geologists in the deep blue dust, scratching their heads and wondering how they got it wrong?

West concedes the possibility that this object could be an entrance of sorts, in the same way that the action of moving water can form caves below the surface.