Complex sentence: As the planet is engulfed by fiery destruction at the hands of those who were sent to establish contact with its denizens, Tempe finally realizes what the Quintans are-the mounds-but he has no time to share his discovery with the others.
Split into simpler sentences: As the planet is engulfed by fiery destruction at the hands of those who were sent to establish contact with its denizens, Tempe finally realizes what the Quintans are: the mounds. However, he has no time to share his discovery with the others.