Functionally identical to the Cyberdiscs of the First Alien War, except miniturised for indoor-use, Bio Drones are terribly dangerous.
The usual Cyberdisc warnings apply here:
1. Use anything other than a Melee weapon against it with cause an explosion big enough to kill creatures nearby... Aliens, civilians, or your men/women.
2. Though it has a front and back, and therefore possible to sneak up upon it unnoticed, it is physically impossible to tell which way it is facing visually.
3. When possible, double-team against a Bio-drone. Have an aquanaut drawing fire, while another sneaks up behind it with a Melee weapon.