Odd structures on the Antarctic Polar Plateau

I’m watching The Last Place on Earth right now about the Amundsen and Scott expeditions to the South Pole. I just finished Episode 4 last night, where Amundsen’s group reached the Polar Plateau.

Several miles into it, they found some strange structures. They looked like cones, and when Amundsen hit one with his pick-axe, it crumbled. He conjectured they were formed by pressure.

Would anyone have any idea what these cones were? I’ve been trying to find pictures of them, but have not had any luck.

“Tekeli-li !”

"Tekeli-li !"

"Tekeli-li !"

Yeah - I’m thinking they were not entrances to the hollow earth.

Might have been some version of nieve penitentes?

Any google search on any topic should yield a conspiracy theory.
Here’s one about the South Pole: http://www.enterprisemission.com/antarctica.htm

The Russians broke through Lake Vostok more than a year ago now. Hoagland really needs to update that page with speculation on what the Russkies are doing with the Monolith they found.

In Nat Geo a while back there was an article about ice caves in Antarctica formed by geothermal activity. There are cave vents that form chimney-like structures from the freezing condensation. They’re hollow inside and would crumble if struck, I’d think.

The first picture at this link is what they look like. Not really a cone, though.

I think that’s it. Thanks.