They used what was later known as the Jewel of Fawton as a hive mind. The Jewel worked as a consciousness that coordinated the consciousness and nervous systems of each creature. They spoke a language which neither the colonists nor the TARDIS' translation circuits understood.
When the Jewel was taken by colonists as a means of income for tourism, the creatures were in a state of hibernation, and couldn't wake up again until the Jewel was returned by Roget later on. After Roget put the jewel back in place, they awoke. The Fourth Doctor noted that as the jewel was part of them, the colonists had to live alongside them, "without your tourist-trap jewel". (COMIC: A Rare Gem)