Pendulum (Q3)

"Pendulums swing from side to side. Players die when hit by a pendulum so care has to be taken when trying to pass them."

- Quake III Arena manual

The Pendulum is the only Hazard appeared in Quake III Arena on this level Demon Keep. They are large, stone-carved crosses suspended from ceilings, swinging perpetually. They’re normally found with other pendula. Pendula are best avoided by quickly moving into its position before it hits you, then squishing into the meaty chunks of death on one blow to the next.

They all have the crosses on them.