What became a major form of wall decoration during the Romanesque period? Why?

Drum columns

In most parts of Europe, Romanesque columns were massive, as they supported thick upper walls with small windows, and sometimes heavy vaults. The most common method of construction was to build them out of stone cylinders called drums, as in the crypt at Speyer Cathedral.

motet will be the answer; ///

c. shubert i think : )