The mass of men stared at me and did not move.
The mass was moving with all its combined force toward the door.
The black mass didn't move, although it surely should have heard him by now.
There was confusion for just a moment, then the mass of hair moved.
He looked down the canyon again, and this time saw a dark green mass moving toward him.
He had felt that the great mass of rock was moving, pressing down upon him.
During the minute or so that we could see some detail, a large black mass moved south across the ice.
The main mass must have been moving at close to a metre a second.
While he was busy with that action, the mass of blackness moved from behind the table.
A projecting mass of black moved slowly into the inner office.