Oxide shark

Not actually this green. What you want is this.

The poisonous oxide shark is the deadliest predator in Cybertron's Rust Sea. Travelling in schools (or shivers), they don't take kindly to intruders to their territory. A usual response involves one oxide shark turning into their torpedo mode and blowing the offender out of the water. They're bright green.

Fiction

Toy bios

Devastator chose a bright green color scheme at some point in time, taking the color from the oxide sharks of the Rust Sea. He wanted everyone to know destruction was coming - and that nothing could stop it. Toys"R"Us-exclusive Devastator's on-line bio

Beast Wars: Uprising

After one Game at Dodecahex ended with a contestant trying to flee by the river, the Builder Override had the nearby river filled with alloygators and oxide sharks. Afterward, any Game set there would inevitably feature some poor sap with an aquatic alt-mode, so the audience could watch the sharks torpedo them. Broken Windshields

At Megatron's urging, Overbite attempted to scan an oxide shark for a new alternate mode. The experimental beast mode process was only partially successful, leaving Overbite a malformed mixture of shark and submarine. Not All Megatrons

Several aquatic Resistance troopers participating in the battle for the Yuss Straits had oxide shark beast modes. Derailment