The reality is rather mundane. These pyramidal peaked mountains do exist in the Ellsworth range, and are well-documented. Also called a "horn", they are one of the features of glaciated areas; these "horns" form from the convergence of glaciers that scour the sides of an existing landmass. They often form as the result of sharp circular erosion, due to the multiple glaciers which diverge from the same central point. These pyramidal peaks are often called "nunataks" and are not just a feature of the Antarctic ice shelf. The famous Matterhorn Peak is perhaps the world's most visual example of such a natural formation.
However, their continued existence on the ice shelf makes them easy to peddle as clickbait, and they are often run as the same. They were debunked first in 2017 after the claims went viral in 2016 and have been covered by the History Channel as well. The last word on this topic belongs to Eric Rigot, a geology professor at the University of California, Irvine who provided an iconic quote on the story to LiveScience in 2016.