Gem Drill

Plot

Continuing directly from "Super Watermelon Island", Steven tells Peridot they must stop the Cluster, an underground geo-weapon that could destroy Earth. They climb into their drill and begin tunneling. During the descent, they discuss Peridot's former life on the Gem homeworld versus her life on Earth. When Cluster prototypes—artificial, deformed fusions of broken Gem shards—attack the drill, Steven fights them off but feels uneasy about not helping them.

The drill reaches the Cluster, a huge sphere of millions of Gem shards trying to take physical form but not yet able. Peridot prepares to drill into it, but cannot pierce its surface. Knocked unconscious, Steven has a vision where he floats among the shards and realizes he can communicate with them; they are obsessed with taking form to feel whole. He suggests they might only need each other's company.

The shards converse but cannot resist forming. Steven bubbles a few shards, then wakes to see the shards slowly bubbling each other. He merges all bubbles into one huge bubble encasing the Cluster. After returning to the surface, Pearl, Garnet, and Amethyst arrive with an unconscious Lapis Lazuli, and Steven recounts what happened. The final shot shows the Cluster peacefully lying deep in Earth inside Steven's bubble.

Broadcast and reception

The episode aired on May 12, 2016, as part of Cartoon Network's "In Too Deep" special event, which presented five new episodes over four weeks. Its initial American broadcast drew approximately 1.693 million viewers and a Nielsen household rating of 0.46, meaning 0.46% of households watched. Reception was mixed: critics praised the drilling scenes, creepy atmosphere, and Peridot's characterization, but many found the Cluster arc's conclusion—where the shards bubble each other—unsatisfying, rushed, and anticlimactic. Eric Thurm of The A.V. Club gave the episode an A.