After the end of the First Formic War when its properties were first able to be studied properly, researchers believed that it contained silicon and was essentially weaved by microorganisms created by a Hive Queen, giving it its strength.
Hulmat was first engineered by the Formics sometime after 300-600 BX, as that was when the last known Formic Ark left the Formic Homeworld. The Ark was carved out of an asteroid and did not use Hulmat, so it must have been developed afterward.
Humans first encountered Hulmat during the El Cavador, WU-HU Corporation, and Makarhu attempt to destroy the Formic Scout Ship. Oddly, the explosives the miners used on the hull worked, blowing gaping holes.
After the war had ended and researchers could get a look at the hull, they were astounded by how strong it was. Juke Limited built a research station around the scout ship in order to study Hulmat and spent the next three years doing so. In 97 BX, with the help of Wilasanee Saowaluk and Dr. Noloa Benyawe, Juke developed the NanoCloud, a swarm of nanobots that could discover the fibers used to create the ship and unwind them in order to more effectively penetrate the hull.
- In regards to why the El Cavador miners were able to penetrate the hull, Aaron Johnston, the author of the series, stated that there would be an answer given in forthcoming books.