The Seed Spawn is the first and larval stage of the Spawn life cycle.
The Seed Spawn is small and slug-like, a mere 0.5 foot long creature, with a mouth-like orifice. When a host is spotted, it will 'flip-flop' towards it or 'slide' towards it, although in the first 2 games it is a very slow organism which attacks in groups of 30 or more. It's coloration is brown or red. In Total Assault 3 several different types are noticable, the fast red ones which flip flop, and the slow brown ones which are consistant in the first 2 games, there are also slow green ones that explode when shot.
Seed Spawns are created in Mega Spawn colonies by a Queen Spawn. At this point they are already ready to continue reproduction, however, they spew constantly in a froth-like substance from the mouth of the Spawn Core. When it is ready to find a host, the Seedling will find a Host and burrow into the Host's head, and target its Pituitary gland. When in control of the Pituitary gland, the Seed Spawn will begin to change the host, feeding it, keeping it alive, so that it may create more Seed Spawn like itself. The host will be changed into a killing machine, known as a Warrior Spawn. The Warrior Spawn's appearance will vary based on which host it is. After several hours go by the host will be a walking colony of immature Seed Spawns, which will leave the colony as they mature and go on to search for a new host. Eventually only the original Seed Spawn will be left, along with several strands of the original host's DNA. When this original Seed Spawn goes off to infect another host, it will carry the previous host's DNA onto the next host creating a Hybrid creature. When this Seed Spawn has infected enough hosts it will become an Over Spawn and will have the ability to Mutate at will. As the Over Spawn mutates it will mature, and eventually become a Queen Spawn. The Queen Spawn is bloated and immobile except for several appendages on her torso. The Queen Spawn has the ability to create Mega Spawns at will and en masse, bolstering the growth rate of a Spawn Population. At this rate, with even no more than one Queen, a Spawn colony has the ability to spread over an area the size of Russia in no more than a few hours. With multiple Queens a Spawn invasion will take Earth in no more than one. If a Spawn Queen has lived long enough it can become a Spawn Core. The Core's main purpose is to serve as a mobile base, Spawn will live and thrive inside of it, and it is constantly spewing forth fresh Seed Spawn, The Core also issues all of the orders to local Spawn and Spawn onboard orbiting ships. A Core's call can be heard light years away, but only by other Spawn.
Seed Spawn only possess their animalistic drive to feed and reproduce, other than that, Seed Spawn are relatively unintelligent. They do however possess the ability to cut the power of a facility to slow down its prey, or target the source of a weapons cache and destroy an entire armory, which would also slow down the enemy.