Anyone remember habitrails? They were those cool plastic tubes you could join together in vertical and horizontal “tracks” for pet hamsters and gerbils. I had a set as a kid. My hamster loved them. Unfortunately, they weren’t cat proof.
A childhood lesson in survival of the fittest.
Anyway, Mike Bara and Richard Hoagland think ancient Martians built glass tubes on Mars. For some reason.
Over at the Emoluments of Mars, Ex-Pat has a brief debunking of the glass tubes, with a series of excellent links to serious science that explains the features.