Oxygen Algae

Oxygen Algae (氧气藻; pinyin: yǎngqì zǎo) is a plant in Plants vs. Zombies: Journey to the West and Plants vs. Zombies Online. It is an aquatic plant, and as such can only be planted underwater. Since most plants cannot be planted underwater, the Oxygen Algae must be used. When planted, the player will be able to plant any other plant in an area around it.

Plants vs. Zombies: Journey to the West
Oxygen Algae is obtained in the Underwater World. It provides oxygen in a 3x3 area around itself.

Plants vs. Zombies Online
Initially, Oxygen Algae releases oxygen in a cross shape around it to let land plants survive in the aquatic environment. It has a meter below it with 3 sections, which is used to show the level of Oxygen Algae. The player can click on the Oxygen Algae to level it up by spending some sun.
 * The first level costs 75 sun and make the oxygen-supplying range become 3x3.
 * The second level costs 125 sun and make the oxygen-supplying range diamond shape.
 * The third level costs 200 sun and make the oxygen-supplying range become 5x5.

Plant Food effect
Its Plant Food ability is currently unknown.

In General

 * Algae is actually neither plant, animal, nor fungi. Algae is usually a single-celled organism, however, multicellular algae is not unknown to exist.

Specific to Plants vs. Zombies: Journey to the West

 * If it gets eaten, the player has 5 seconds to plant another Oxygen Algae before all plants in the 3x3 area where the Oxygen Algae was drown.

Specific to Plants vs. Zombies Online

 * Oxygen Algae is the first plant in Plants vs. Zombies Online to be upgradeable during the level without help of a seed packet.