And while it looks flat on top, it probably has a more iceberg-like geometric shape under the surface.
In a different photo, Mr Harbeck captured both the edge of the now-famous iceberg, and a slightly less rectangular iceberg.
The IceBridge mission began back on October 10th but it's far from over.
This isn't the only iceberg news we've been treated to lately. Larsen C itself calved an even larger iceberg in 1986, Shuman said.
This is near the Larsen C ice shelf, where NASA believes the iceberg has recently broken off from - evidence of a recent break comes from the fact the iceberg has sharp edges.More news: Ruben Loftus-Cheek happy with competition at Maurizio Sarri's Chelsea
Its precisely cut corners show that it hasn't been around that long, because the sharp edges would become round from exposure to wind and waves.
The iceberg was spotted by senior support scientist Jeremy.
However, tabular icebergs are vast slabs of ice with a flat top and vertical sides that form by "calving" or splintering off a much larger ice shelf.
"[Icebergs] look like these attractive pristine white things from a distance, but if you look a little closer, they're really mangled and full of cracks", she says.
It's hard to tell exactly how big the iceberg is from the photo, but experts said it was probably more than 1.6km (1 mile) across.
Ice Bridge is spending several weeks measuring changes in Antarctic sea and land ice while flying under orbits of ICESat-2 to compare measurements.
Just past the rectangular iceberg, which is visible from behind the outboard engine, IceBridge saw another relatively rectangular iceberg.