Collapsible Floor
From WikiRaider
The Collapsible Floor can be harmless, if not combined with another trap. Underneath you may find Lava Pools, Firetraps, Spikes, an Abyss, Acid and more. Except in a level in Peru in original Tomb Raider and Tomb Raider Anniversary right before your first encounter with the raptors.
You'll find a collapsing floor combined with Floor Spikes in the Tomb Raider II level The Great Wall or in Chronicles, Gallows Tree.
