A couple of assumptions here. The first is that our solar system has habital planets from their perspective, I wouldn't completely rule out that there chemistry

A couple of assumptions here. The first is that our solar system has habital planets from their perspective, I wouldn't completely rule out that there chemistry could be very different to ours. The second is that they need habitable planets. The idea of living in under ground tunnels isn't palatable to us because we evolved in wide open savanahs, an underground, underwater or nocturnal species might not feel the same.