Tip: When making your overworld, mix the terrain up! Add decorations to the overworld. Don't leave large empty grass or sea regions. As an example, angled land and multiple colors look much more interesting than square land and flat, plain colors.
This is a pipe cannon from NSMB that if the player enters it, instead of warping to another level, shoots the player straight up into the air (you cannot control during being launched). Mario will keep going until he hits a ceiling, or 2 custom blocks: PipeCannon_End.asm or PipeCannon_teleport.asm. Useful for a gimmick like getting to high areas disguised as a pipe to nowhere.
Bug: If Yoshi's on the center of the cannon and Mario enters it, he will automatically get on him while shooting himself. Also when Mario gets in the pipe and $9D is set, some sprite tiles get glitched up and some parts of Dino Torch fire disappear.