Life Counters

Life Counters were non-canon circular devices included with some of the sets of 2009. They had a scale from 5 going down to 1, plus a skull marking for "death", or, "defeat", that was between the 1 and 5. They were used in the "BIONICLE Action Figure Game."

Glatorian Arena & Glatorian Arena 2
In the BIONICLE online games, Glatorian Arena and Glatorian Arena 2, there was an animation in each upper-hand corner to keep track of the life for the character controlled by the player, as well as the computer.

Function in Canon Storyline.
The Life Counters on the back of most Glatorian in BIONICLE: The Legend Reborn have been confirmed to be small back packs.