Tangle Kelp

The Tangle Kelp is a one use, instantly armed aquatic trap, dragging any zombie unfortunate enough to cross its path into the watery depths of the Pool.

Usage
Place a Tangle Kelp in any water lane, and it will take down the next single Zombie that touches it. Note that it can only trap ONE zombie, so if there is final wave and you use a Tangle Kelp it will only trap that zombie.

Suburban Almanac Entry
Tangle Kelp

Tangle Kelp are aquatic plants that pull the first zombie that nears them underwater.

Damage: massive

Usage: single use, on contact

Must be planted in water

"I'm totally invisible," Tangle Kelp thinks to himself. "I'll hide here just below the surface and nobody will see me." His friends tell him they can see him perfectly well, but he'll never change.

Cost: 25

Recharge: slow

Strategy
With such a low cost, Tangle Kelp makes an ideal early defense in pool lanes. Just don't get lulled into failing to build up your pool defenses, because the slow recharge prevents Tangle Kelp from being readily re-used.

They also take down Dolphin Rider Zombies whole instead of being jumped over, so these may be more useful than just placing a Lily Pad in front of it. Furthermore, they are useful in defeating Snorkel Zombies, as they can drown them without having them come up. However, their slow recharge may prevent them from drowning every Dolphin Rider Zombie or Snorkel Zombie, so it's wise to prepare backup plans for them just in case.

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Trivia

 * The Tangle Kelp, Hypno-shroom, and the Chomper are the only Instant Kills that are not Area of Effect plants.
 * The Tangle Kelp is the only attacking plant that Dolphin Rider Zombies can't jump.
 * Along with the Sea-shroom, the Tangle Kelp is one of two offensive plants that don't require Lily Pads to be in the Pool.
 * The Tangle Kelp, the Sea-shroom, the Grave Buster and the Cob Cannon are the only plants that cannot have Pumpkins placed around them, excluding the Pumpkin itself.
 * The Tangle Kelp cannot tangle the Bungee Zombie and make him drown.
 * When being stolen by a Bungee Zombie, the Tangle Kelp still animates its ripple animation on the air.
 * Same with an unarmed Potato Mine - only the flashing light thing is shown.
 * It´s unknown how the Zombies can drown, as they don't have to breathe, which is stated in the description of the Snorkel Zombie.
 * However, they might be strangled to death by the Tangle Kelp.
 * Then again, zombies might not die due to strangulation. Instead, the Tangle Kelp could have just cut his head off, or eaten.
 * It also is possible that Tangle kelp kills zombies with water pressure as stated that Snorkel Zombie uses snorkel to control the pressure.
 * The Tangle Kelp, the Chomper, the Potato Mine, the Hypno-shroom,and the Squash are the only Instant Kills that are used on contact with the enemy.
 * The Tangle Kelp is the only aquatic instant kill.
 * On the Plants vs. Zombies website the Tangle Kelp is seen on land, other than in the water.
 * In the Almanac entry of Tangle Kelp, it says that it thinks Zombies cannot see him. This may be true due to the fact that Zombies never eat him, and Dolphin Riders keep on riding past, when they would normally jump over.
 * Tangle Kelp is one of the twelve plants that appear in the seed selection screen, after you get the Grave Buster on the online version. The others are: Ice-shroom, Lily Pad, Potato Mine, Threepeater, Doom-shroom, Jalapeno, Spikeweed, Torchwood, Tall-nut, Cactus and Blover.
 * Tangle Kelp and Potato Mine are the cheapest massive damage plants.
 * Tangle Kelp (not including the Imitater Tangle Kelp while transforming), Spikeweed, and Spikerock are the only plants that can't be eaten.
 * Tangle Kelp is basically the aquatic version of Potato Mine except it doesn´t need time to arm and is not AoE. However it costs the same amount of Sun.
 * The Tangle Kelp also looks like the Pokemon named Tangela.
 * Biologically, the Tangle Kelp is not a plant; it is a protist.
 * It is unknown what happens to Tangle Kelped zombies after they are pulled underwater.
 * Maybe they are the zombies that surface at the start of a huge wave.
 * But then again the zombies that are pulled under are probably killed.
 * In Imitater Tangle Kelp's seed packet, we cannot see the down part of it.
 * The bottom of a tangle-kelp's body basically just looks like a knotted, green rope.
 * Tangle Kelp, Chomper, and Squash are the only non-explosive insta-kill plants.
 * No matter, how many Tangle Kelps you use in one level, your pool will never be full of zombie corpses.
 * Tangle Kelp can only take down one zombie,unlike squash and potato mine.