Due to the rank environment of the time period, food supplies are scarce. The inhabitants of the Arris Dome rely on Enetrons for sustenance. Discovering this, Crono, along with Marle and Lucca venture through the sub-levels in search of food and an explanation to the desolation their world has become. Before heading down, they are warned that several others attempted to investigate the sub-levels and never returned.
Beneath the dome, the passage forks two ways. One is accessible, while the other is mechanically locked.
On their mission, they discover Guardian and the two Pods are the source of the missing inhabitants. This is the third boss battle of Chrono Trigger. Defeating the robots, the teams discover a food pantry. All supplies within are rotted beyond salvaging due to the refrigeration system having failed after hundreds of years of neglect. Only a single Seed survives. They claim the seed. On a corpse in the pantry, a note is discovered, detailing that the password to the locked corridor was stolen by a rat.
On their way back through the sub-level, the rat is discovered and chased down. Recovering the password, Crono and his friends travel into the locked passage, fighting several malfunctioning robots and vermin along the way. At the end of the corridor, they discover a room with a computer. Marle accidentally accesses a news feed on the machine and it displays on a nearby screen. Here, the party watches a video-diary of several citizens from 1999 A.D. moments before a parasitic alien emerges from the planet's crust and rains fire down upon the civilizations there. A Time Gate is also discovered in the computer's archives.
Vowing to use their time-travel ability to prevent the destruction of their world, the party heads to the surface.
Topside, the Arris Dome citizens are amazed that the party survived the dangerous sub-level. Crono hands over the seed they found and advises them to plant it to replenish their food supplies. Previously pessimistic about their situation, the survivors are given a new sense of hope and agree to plant the seed. When the dome is visited later in the game, several potted plantlings are seen throughout the dome.