X-Plo gel

X-Plo gel is some sort of explosive, presumably in a semi-solid state.

Fiction

Web of Deception

After the mysterious disappearance of Optimus Prime, the Autobots tracked down Lockdown, who claimed that the Autobot leader was "snoozing on the lakebed in a diving capsule — packed with enough X-Plo gel to blow him back to Cybertron!" As Blackarachnia later had a video of Optimus tied to a solitary canister, it's unclear whether Lockdown was exaggerating, or if that's all the X-Plo gel that was needed. Web of Deception