God Mode
20 Achievements
400
25-30h
Embryo
Destroy 50 scarab eggs before they hatch
10
How to unlock the Embryo achievement in God Mode - Definitive Guide
The level Fortress has a section with lots of eggs in it, towards the end of the level, and it's very good level for leveling up in the beginning since it's pretty easy so getting the 50 eggs should be a breeze.
Scarab eggs can be found in two ways: first, there are a couple of levels that have them as part of the stage; second, they can be spawned by Breeders. What you have to do is find them (they look like large green eggs, fairly easy to spot) and destroy them before they hatch. The easiest way to farm this is to do Basilisk Pit a few times, as it has a large number of them on the level which are easy to destroy without them hatching.
Scarab eggs are green and black eggs which will eventually hatch out enemies known as scarabs. Simply destroy them in the egg state until it pops (no pun intended). A good map for this one would be either Fortress or Basilisk Pit. Scarab eggs can also be sent out via Breeder enemies. There is a Breeder on the map 'Basilisk Pit,' and if you can manage it you can avoid killing it and let it keep shooting the eggs onto the floor, at which point you can shoot and destroy them.
If you are unsure what Scarabs or Breeders are or what they look like, you can visit the bestiary in the main menu and see them.