What is this mysterious formation?

[Ivan Seeking]

http://www.coasttocoastam.com/gen/page2381.html?theme=light

My first thought was that it may be an ant hill, but the photographer says it was a rock. I would still think it to be a petrified something?

 

[waht]

This area was certainly underwater. I suppose a vortex formed which grinded a funnel into the rock formation over eons. The river is pretty stagnant, but there were times when a rush of water from melted glacial dams flooded the area with intense surges of currents.

 

[NoTime]

Kinda looks like limestone.
Perhaps a spring or possibly a steam vent.

 

[hypatia]

Looks like a place where a mineral spring once flurished. I have even been to a city named Mineral Springs in ND, so its fairly common for that area.

 

[waht]

A mineral spring or vent makes more sense.

 

[matthyaouw]

Mineral precipitate around a spring was my first thought as well. Would be helpful to see a bit of it up close and know something about the area it was found into say for sure.

 

[Andre]

A look-alike in Yellowstone park:

http://www.naturalsciences.org/education/Yellowstone/2006/images/unusual%20hot%20spring%20at%20Mammoth%20Terraces.jpg