Boulders
From WikiRaider
The Boulder (aka. Rolling Ball) was always a famous trap in the Tomb Raider Games. The boulder on the right is from Tomb Raider 3, but there were also boulders in all other Tomb Raiders.
Besides boulders there are barrels, avalanches, rocks and more that will make you jump out of the way.
Prior to Tomb Raider the Last Revelation, the balls are not physics based, and will only roll in one direction at a constant speed, until it hits a ledge, wall, or a slope that faces the other way. However in the fourth game it is physics based and it bounces and rolls according to the terrain.
The boulder was not featured in Chronicles and Angel of Darkness.
Boulders always kill Lara instantly unless she is in a vehicle. She only bleeds extensively in the first three games when flattened by a boulder.