My forth robot vermin will become my fifth as my fifth bcomes number four. I had been working on these two simultaneously. When the former became too tedious I would switch over to number five.
This robot vermin stands about as tall as a US half dollar or approximently 34mm. The unit represents a intrusion detection sensor. It would, using a small hydrogen fuel cell, fly to it required location. Once there, it would land, the fins would be blown off by the means of a small charge, and using the built in cutting edges the unit would start to drill itself into the ground. Once at the required depth it would connect to the perimeter network and start to do its job in intrusion detection.