034 The Macra Terror by Ian Stuart Black S4 S7: The TARDIS lands in a peaceful human colony, a place that appears to be more of a holiday camp than a settlement. The inhabitants are forced to mine for a lethal gas, essential to the survival of monstrous crab-like creatures the Macra. When Ben too falls under their influence, it is up to the Doctor to destroy the mining equipment and starve them. Some of the only clips that survive are scenes cut out for being too violent.
The uneven nature of the rock makes the squares look like they are moving. The curvature also gives the white boarders a raised look...making me wondering if he managed to use snow or another medium for the effect