Ah, I think you mean the
Bobble Head, right? Yeah, I kinda forgot this one and yeah, it's the most annoying one.
I think lightning tower can hit it but there aren't many towers that can, mostly because towers don't target the weak point. Some enemies are thought anyway to be fought by the player, they are designed to get past your defenses to keep the player at alert and don't afk the whole time. Problem is, the things are even as player a pain in the neck.
I just checked before sending this post, Drone towers ignore armor, even perfect armor (that makes you invulnerable), so they can kill them.
A level 1 drone tower does 200 dps and a bobble head has 3000 hp, they move kinda slow and a drone tower can kill them in 15 seconds, faster, if they are supported by more drone towers, support towers or are upgraded.
An interestign fact is, that one drone does exact the damage (3000) a bobble head has as HP before it expires, prett obvious what they were meant to counter.