Khard'aal: info (Patreon)

These creatures could be compared to "moms", because their main purpose of life - always take care of offsprings, and because growing matrices are too similar to their eggs khard'aals became wonderful assistants for Ancients in this difficult and long-term work - to care for still soft and vulnerable matrices till they will be ready to be removed from its places of growth and placed into spaceships, station cores, armor, weapon etc..

Size comparison:

And here I found some old sketches with matrix generators and places of growth of matrices themselves:

Also those places could be found only on spaceships, even in old times Ancients removed all "gardens" away from Reagkhay to protect them from tsaruras and one more, even bigger, threat, which was under the planet's surface for a long time, till was awakened by explosion during Ancients' experiment of connecting the worlds (our and Matrix).