Physical Description Edit
The pipes exists in several colours, but the most common one is the green. The sentient pipes look exactly like the other ones, and are faceless despite being living characters. However, one of them was seen wearing glasses.
Appearances in SuperMarioGlitchy4's videos Edit
Pipes appeared in many bloopers of SMG4, but "Problematic Pipe Problems" is (actually) the only video in which they appear as living characters, and it's then their first and most prominent appearance.