Sea-shroom

Sea-shroom is the 25th plant unlocked in Plants vs. Zombies. It is the aquatic version of the Puff-shroom, but it has a slow recharge time. It is the first plant obtained from the Fog levels and it shoots purple spores at incoming zombies.

Suburban Almanac Entry
Sea-shroom

Sea-shrooms are aquatic plants that shoot short ranged spores.

Damage: normal

Range: short

Must be planted in water

Sleeps during the day

Sea-shroom has never seen the sea. It's in his name, he's heard loads about it, but he's just never found the time. One day, though, it'll go down.

Cost: 0

Recharge: slow

Strategies
Plant Sea-shrooms on the third and fourth columns from the right side of the lawn, and try to put a column or two of Fume-shrooms behind them.

In the second and third columns from the left, it is a good idea to plant Scaredy-shrooms as backup. You may want to plant defensive plants in front of them, although this is unnecessary. The Sea-shroom has a slow recharge rate, as it covers two rows less than the Puff-shroom. But this means that you can't easily replace Sea-shrooms that are eaten, making them a lot less disposable (although purchasing the Imitater helps a lot). However, it is not a very good idea to use it for the Dolphin Rider Zombie to make him lose its dolphin, as its recharge cost takes a lot of time unless you have the Imitater Sea-shroom. A Puff-shroom on a Lily Pad is effectively the same, although it costs 25 more sun. In Survival: Endless, you can plant these in the first few flags; you can plant a few of these to slow the zombies down. Also note that, unlike the Puff-shroom, Sea-shrooms are not immune to the projectile attacks from the Peashooter Zombie and Gatling Pea Zombie.

If you are in a hurry to get lots of cheap defense on Fog levels, you are much better off using Puff-shrooms on Lily Pads. It only costs 25 suns per Puff-shroom and is immensely quicker recharging than using Sea-shrooms. Sometimes it is very inconvenient that the Sea-shroom has a slow recharge. Using Imitaters helps you set up one for each pool lane in almost no time. After the mandatory 30 seconds, you can have four Sea-shrooms at no cost.

Trivia

 * Sea-shroom, Torchwood, and Plantern are the only three plants with visible roots.
 * Sea-shroom, Puff-shroom, Iceberg Lettuce, the Grave Buster in Plants vs. Zombies 2: It's About Time, and the first Tile Turnip planted and the Imitater versions of them are the only plants that cost 0 sun.
 * Sea-shroom and Magnet-shroom are the only mushrooms that are obtained during the fog levels.
 * Sea-shroom and Puff-shroom are the only shooters with a three space range.
 * Sea-shroom is the only plant with a Night Pool background in its Almanac.
 * Sea-shroom seems to have approximately the same height as a Puff-shroom. However, it can be hit by Peashooter Zombies' and Gatling Pea Zombies' peas, while they just pass over the Puff-shroom. This is because Sea-shroom rests directly on the surface just like Puff-shroom, but zombies in the water do not just walk on the water, they sink halfway into it, making their heads almost level with the Sea-shroom's.
 * On the Android, there was a bug where Sea-shrooms can only shoot one to no spaces ahead of them. But it was fixed in the sixth version.
 * While not stated in any known sources, Sea-shrooms appear to be inspired by the real-life species Psathyrella aquatica, which also has never been observed growing in the ocean.
 * Sea-shroom is the only aquatic plant that sleeps during daytime levels and also being the only aquatic mushroom.
 * In the online Almanac entry, it is floating over the grass even though it is aquatic. The same goes for all the other aquatic plants.
 * At the Aquarium Garden, the Sea-shroom's roots look like tentacles making it resemble an octopus.
 * As seen in the concept design for Sea-shroom, it was not going to be a mushroom. It was also a lot bigger.
 * Although it is green, it still shoots purple spores.
 * It is the only non-instant kill or non-upgrade plant with a slow recharge.