How do I collect Oxygen Tanks from a Crate?

Oxygen Tanks are stored in a Crate covering a 2×2 area of the board.

1. Break the lid. Make matches next to the Crate or hit it with power-ups. Some lids take several hits to open.
2. Collect the Oxygen Tanks. Once the Crate is open, each further hit releases one Oxygen Tank. If Oxygen Tanks are part of the level goal, they count toward it as soon as they’re released.

Each Crate holds a limited number of Oxygen Tanks. Matches along any of its sides count, but one hit releases only one Oxygen Tank, even if it reaches several cells of the open Crate.