In Episode 15 titled "The Call" of "Star Wars Rebels" Season 2, after a delegation of space creatures comes to Rebel forces asking help, the crew workers of Rebel alliance protect them against the atrocities done by Techno Union mining operation.
According to the synopsis of the episode, "While on a mission to obtain fuel for the Rebel fleet, the crew works to protect space creatures from the Techno Union asteroid mining operation that threatens the creatures' lives."
The crew had been suffering from a fuel crisis for a long time and it was in dire need to obtain fuel for its ships and war-crafts, otherwise they were in a danger of getting exposed to the Imperial soldiers.
Hence, they decided to visit an asteroid belt enriched with fuel, only to find that it was already occupied by the Galactic Empire. Given that they had no other option, they decided to attack the Imperial troops and overpower them.
However, as they approached the asteroid belt, Ezra began to hear strange sirens sounding sad and depressed. Nobody else could hear anything but Ezra did. Then straight ahead they spotted a group of space animals, known as Purrgills, coming towards them.
Initially shocked, they mistook the creatures for allies of Empire. However, just when Ezra was about to attack them, one of the creatures told him that they had came in peace and that they want help.
At the end of the episode, the Rebels and Purrgills defeated the Imperial forces and retreated to space after fuelling all of their ships. Ezra told Kanan that he actually saw what Purrgills were thinking of and Kanan believed that Ezra had established a deep connection with the space creatures through the Force.
Afterwards, Ezra, Kanan and Hera witnessed Purrgills jumping to hyperspace and learned that it was them who inspired the technology of hyperspace jump in ships.