re: Not easy for the untrained eye...
The tubes are the narrow lines but the crater has these strange tubes also in it. I don't understand whether the crater would form these are more likely the crater exposed them. Also why the crater didn't fill them in.
This would be an ideal place for a Martian city by covering all the tubes and pressurising it. Also it's likely tubes go into the ground outside the crater area. If you look at the longer tube shapes going off to the right they might be usable as a kind of subway if they are hollow too.
If there was underground ice here the potential for a city would be enormous.