Swarm Egg

Swarm Eggs are a bit different than standard Grub Eggs, as their goal doesn't seem to be reproduction so much as it is self-defense.

The Swarms released by Swarm Pods serve as a nuisance, designed to drive potential trespassers away from Annelid breeding grounds and protect the eggs.

Strategy
Swarm Pods are far easier to set off than the other types of Annelid egg pods, so your best bet is to keep your distance if you want to avoid potential Annelid Swarms inside. Alas, sometimes it's not possible as they are cleverly placed around corners that you have to pass. Make sure you know your way back to allow yourself some running space.

Swarm Pods, like Grub Pods, can be mounted on ceilings and walls as well as floors, and are often hard to spot, or simply unavoidable. If you release an Annelid Swarm from one, don't bother shooting the Swarm Pod. Search it for potential goodies instead.