What is MissingNo. really?

I hear a lot about MissingNo. like:MissingNo. is a fossilized ariodactyl,MissingNo. is a giant cube of black and white,MissingNo. is a Pokemon that was released in gen 5,and so on. I want to know what it is in gen 1-5. I`m very confused on what it is, so can someone help me?

Pleaselog inorregisterto add a comment.

Missingno means “Missing number,” which in itself means “Cannot findPokemon identity.” In pokémon Red and Blue, there were various ingameplaces that would use up memory slots that other bits of info neededto use. In other words, it’s like putting a brick in a wall, and thennot having any space left to put more bricks in. The result was"Missingno," effectively an error which meant the memory locationcould not be read and was a placeholder. There were a very variations,which you can find under the article linked to in the source.Missingno could cause game crashes, since it’s memory location wouldcause issues. When captured, it would often turn into another pokémon(I remember catching one and it turning into Kanghaskhan). Basically,it wasn’t a pokémon, but an error working under the laws of pokémon.If you encounter one in your game, it’s probably safest to turn offand restore to an earlier save, as any interaction with it could causeyour entire game to crash and you lose all your data.

http://bulbapedia.bulbagarden.net/wiki/Missingno.

it is actually a baby kangashkan I think or something… because it evolved into kangashkan like Flare said. more on thathere