I had heard of the chirping systems, but had never seen one. Yesterday I found a system with an M and an L, numerous unremarkable ice balls around them, only two landables, but every body in the system made bird noises. I also notice that I encountered three unknown signals in the systems, which is very unusual. I normally find none, sometimes one. Because of these anomalies, I spent a good while exploring, but didn't find anything else of note.