Sonic disc

Sonic discs were sonic weapons devised by the Sea Devils when they ruled the Earth with the Silurians. They served as a kind of heat ray, capable of scorching ships and sinking them.

History
The Sea Devils used sonic discs when they awoke in 1972 and again in 2084. They had a similar larger cutting device for cutting through doors. (TV: The Sea Devils, Warriors of the Deep)

The Silurians also used sonic discs, but with bigger and longer handles. These could kill Silurians and humans. (TV: The Hungry Earth/Cold Blood)

Behind the scenes
The toy release of the Sea Devils calls the sonic disc a heat ray.