The Planet Eater is a tool added by Avaritia. Planet Eater does not use durability.
Shift right-clicking with the Planet Eater will put it into "destroyer" mode, and shift right-clicking again will put it back into normal mode. Breaking a block with destroyer mode active will destroy all blocks in an 8x8 cube. Instead of dropping all of those items, one Matter Cluster will be dropped with all of the items inside of it to avoid lag.