Spiny Shell

The Blue Koopa Shell, also known as the Spiny Shell, is an item from the Mario Kart series and a power-up in New Super Mario Bros.. Its effect and appearance differ in the games.

In the Mario Kart series, the shell has wings, and in most games spikes. The blue shell can be shot from second place to twelfth place, regardless of what is in the way, it will home in on the character in first place and cause them to spin out.

The only ways to avoid being hit by a Blue Koopa Shell is using a mushroom right as the blue shell begins to slam into the kart, letting the person in second momentarily take first just before it completely homes in, and entering launching parts of a course, such as the barrel from DK Mountain.

In New Super Mario Bros. the shell is used to roll around like a normal green or red shell from a Koopa Troopa or Paratroopa when the shell is kicked. This makes it easier for Mario to get rid of enemies.

In earlier games
In Mario Kart 64 and Mario Kart: Super Circuit, when fired, the Spiny Shell (referred to in the instruction manual as the Blue Spiny Shell) will travel along the middle of the track until it hits the racer in first place, knocking out any racers in its path along the way. Similar to the Red Shell, the Spiny Shell will break if fired at a wall and it is not able to clear some larger jumps. As the shell cannot be broken by other items or racers, many players find it extremely useful to hold the Spiny Shell behind them indefinitely, thereby protecting them from any items or racers approaching from behind. The only way for the first place racer to avoid being hit by the shell is to use a Starman or Boo. Players between the leader and the racer who fired the shell can simply move away from the middle of the track to avoid being hit.

Since Mario Kart: Double Dash!!
Since Mario Kart: Double Dash!!, the item’s use was changed significantly and had wings. When used, the shell will immediately fly to the racer in first place, hover for a few seconds, and make contact with the racer to make a blue explosion similar to that of a Bob-omb. When used in first place, the Blue Shell will fly around the course and target the person in first place, in this case, the one who activated the shell. The affected racer is flung up into the air, losing a few seconds.

Mario Kart DS
In Mario Kart DS, there is a trick you can learn that will allow you to dodge Spiny Shells nearly every single time you encounter them. The only real limitation is that you must be able to powerslide, which might not be practical on some parts of certain tracks. Also, you must be playing on 100cc or higher (which includes Wi-Fi).

Dodging shells will be much easier if you have prior knowledge of the shell's existence. If you don't know the Spiny Shell is on the field until you hear it hissing then you'll have to be much quicker to dodge it. Make a habit of scanning the item list on the bottom screen often so you'll have time to prepare after seeing an opponent launch it.

When the shell finally reaches you, it will hover over your kart for about a second, then spin over your head once, and then finally drop quickly and explode. Timing is absolutely crucial here, so pay attention. By the time the shell is hovering over your head and starts spinning, you should have red sparks. As it finishes the spin, it will pause for a split second in midair before it starts to drop. At this point, turn hard in the direction of your powerslide (so if you were sliding to the left, press left to make your turn tighter). Just as the shell drops, release the powerslide and immediately start a new one in the same direction. If done correctly, the speed boost from the mini-turbo combined with the extra hop from the second powerslide will cause the shell to miss and explode harmlessly behind you.

It takes a fairly good amount of practice to be able to pull this off for the first time, and even more practice to get to the point where you'll dodge them without fail every time, but it's totally worth it and it helps a lot in getting 3-star rankings in GP. Check out the video to the right for a more detailed tutorial.

An easier way to dodge the blue shell is to get out of first place before it enters the touch screen.

Mario Kart Double Dash!! and Mario Kart Wii
In Mario Kart Double Dash!! and Mario Kart Wii, it is possible (though difficult) to dodge a Spiny Shell provided you have a Mushroom handy. Just as the shell drops (you literally have just a few split seconds) activate the mushroom. If your timing is right the shell will miss and explode harmlessly behind you Unfortunately, it is very rare to have a mushroom in first place, so this trick is of limited usefulness. If this is the case, you might as well take a couple opponents out with you. When you hear the siren, check your rear-view camera and brake and/or swerve to get near one or more opponents. Hopefully they'll be inside the blast radius when the shell takes you out. In Mario Kart Double Dash it is not so smart. In Rainbow Road, the Blue Shell will sometimes miss and will explode behind you without harm. In Mario Kart Wii, the Blue Shell might also miss you when you enter a cannon in Maple Treeway, DK Summit, Rainbow Road, or DK's Jungle Parkway, provided you entered it at the right time. If the shell continues to make the sound while you are in the cannon and it doesn't explode behind you, you have timed it wrong and the shell will come back for you, although it takes a long time, considering that the distance between the cannon and the destination is usually long.

New Super Mario Bros.
In this game, the Blue Koopa Shell is a collectible power-up with a priority higher than the Fire Flower but lower than the Mega Mushroom. It attaches a Blue Shell from a Koopa to the body of Mario or Luigi, and, if they achieve a certain speed, they withdraw into the shell, spinning along the ground, though still able to jump. This method of travel is slightly slower than usual, but makes Mario invincible to most enemies. It does not provide resistance to any other hazards (fire, spikes, being crushed). Upon colliding with a breakable block as a shell on the ground, it breaks; the shell's direction changes at this or any other collision. Another power it has is if Mario ducks he will hide in his shell and no enemies will notice or attack him.

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