The mantis screamer was a giant winged creature native to the desolate Dinares sector. They were capable of both atmospheric and deep-space travel. The latter may have been accomplished while in a larval state. Originally, the mantis screamers were born with a stinger of considerable size on their tails, but at some point in their history, glave parasites infested a rather large clutch of screamer eggs. The parasites consumed the embryos' stingers and took their place, modifying the screamer's tail accordingly.
The mantis screamer nested in towering aeries. These are common sights on lifeless worlds spread over multiple star systems. When the species was absorbed by the zerg many aeries were left abandoned.
The zerg mutated the mantis screamer into the mutalisks. Their morphology changed little and the aeries formed the basis of the zerg spire. The mantis screamer's nesting form was the basis for the guardian mutation.