Underground base ventilation cap on Martian surface?

With the presence of water and moderate surface conditions Mars is the focus of much scientific study and the possibility of human colonization.

Various possibilities are under investigation; one of the more popular options is building living quarter’s underground. This would significantly lower colonists’ exposure to radiation.

Did Mars Curiosity Rover discover an underground base with a vent cap protruding from the Martian surface?

Underground base ventilation cap on Martian surface
Underground base ventilation cap on Martian surface (click for larger image)

In this image taken on Sol 721 an object, which appears to be a vent cap similar to an equivalent on Earth, is seen nestled between the rocks.

Conventional ventilation cap found on Earth
Conventional ventilation cap found on Earth

Original NASA source: https://mars.jpl.nasa.gov/msl-raw-images/msss/00721/mcam/0721MR0030860060402822E01_DXXX.jpg

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