The Deep Child is a specialized, genetically engineered Mycon spore pod. Unlike the typical Mycon, a Deep Child is about 25 meters tall when it hatches from its "egg." The Deep Children aggressively terraform planets for expanding the Mycon's Sphere of Influence. Most of the information on the Deep Children comes from analysis of the Deep Child Egg Case Fragments, the Syreen account of the destruction of Syra, and comments from the Arilou, Druuge, Melnorme, and the Mycon themselves.
A Birthing Fleet, also known as an "implantation fleet", usually accompanies the Deep Child to the intended planet, protecting and assisting it in its inert form. While a Birthing Fleet is present at the attempt to colonize the Organon star system, the Syreen did not mention any unknown alien fleets when Syra was attacked. After the Birthing Fleet launches the spore pod at the planet, the egg case glows white as the Deep Child speeds through the atmosphere, possibly the same thing that the Mycon call spears of light (or "Spears of Light" in the Syreen dialogue). The Deep Child strikes the planet with so much force that solid rock flows like liquid. The egg case that allows the Deep Child to survive the impact is discarded as the Deep Child penetrates through the planet's crust. The Deep Child burrows down to Mohorovichic Discontinuity, the transitional area between the crust and the mantle, hence the name "dwellers in the Mohorovichic."
Once embedded beneath the crust, the Deep Child grows several, fibrous tendrils in all directions. These tendrils then thrust upwards, creating huge calderas all across the planet surface. This process can take anywhere from a few months to a full year. From the huge calderas, the planet's atmosphere is filled with clouds of super-heated steam and sulphuric acid. The planetary crust is completely broken apart, and hot magma flows across the surface in large rivers. No longer a vibrant Water World, the new Shattered World is ready for Mycon colonization.
- See also: Mohorovičić discontinuity