Rust worm

Rust worms are voracious, writhing creatures that inhabit the Sea of Rust. They feast on metal and any Transformer unfortunate enough to enter their domain will quickly find themselves entangled and devoured.

Fiction

2019 IDW continuity

Though a mythological account held that the Great Rust Sea formed from the nucleon of Primus himself, I Have No Mouth And I Must Starscream the Sea of Rust began with the rust worms. During Cybertron's Age of Expansion, the worms discovered the metal planet and began feasting on its innards, secreting liquid rust as they consumed. When the greatest minds on Cybertron failed to contain the animals, the planet did so itself, forming an impenetrable basin that halted the worms and forming the Sea of Rust. Sea of Rust I