Matter dissolving bomb

A matter dissolving bomb — or MD bomb for short — was a device that, when detonated, broke down matter in its blast radius.

After the Fourth Doctor was tied up with artificial ivy vines in the Kraal reproduction of Devesham on Oseidon, Styggron placed an MD bomb at his feet and primed it. With his training of the Kraal androids complete, he intended to destroy the village and the Doctor with it. Sarah Jane Smith used the Doctor's sonic screwdriver to free him with twenty seconds remaining. They managed to evade the blast and the village was left a barren landscape — i.e. the natural surface of Oseidon. (TV: The Android Invasion)