The Morph Ball is an amazing feature that Samus Aran is able to perform in the Metroid series of video games. While many have tried to duplicate it, most notably the Space Pirates, many have failed to do so seeing the amount of deaths that have resulted. It was crafted by the hands of the Chozo species, who added it to their Power Suits that Samus wears.
Once Samus goes into morph ball mode, she and her armor will shrink to the size of a small ball, and will then be able to travel that way, fit through tight paces, lay bombs, travel up walls if they have a spider-track, boost, and do other things as well. Usually in games she'll either 1. have to find it at the beginning of the game or 2. have it at the beginning of the game, though quickly loose it, requiring you to go back out and find it again. This is not the case in Metroid Prime 3: Corruption, however, where you never lost the ability.
The Spider-Ball is an addition to the Morph Ball mode which allows you to travel up certain walls that are plated with Spider-Ball tracks. You are required to obtain this item in the games that feature it, as it'll usually lead you to areas that otherwise can not be entered.
Metroid Prime Pinball
In the Nintendo DS video game Metroid Prime Pinball, a remake of Metroid Prime, Samus was in her morph ball form through the majority of the game, only appearing in her humanoid form during enemy raids. The morph ball would obviously act as a pinball, and could crash through opposing forces and rank up the players' score. The game was highly acclaimed, more so than Fuse Games' (the developer) other pinball video game Mario Pinball Land, which featured a shrunken Mario.
Super Smash Bros. series
In the Super Smash Bros. series, starting with Super Smash Bros. on the Nintendo 64, Samus' down special move would cause her to quickly morph into her morph ball and lay a bomb. If executed perfect she could, as in the video games, perform a morph ball jump with carefully placed bombs. So far, along with the original Super Smash Bros., this attack has been present in Super Smash Bros. Melee for the GameCube and Super Smash Bros. Brawl for the Wii. In the games, however, it was simply called Bomb.
While Samus's arsenal of missile weapons is indeed formidable, her enemies are in for a rude awakening if they guard against nothing else. Her Grappling Beam captures foes and latches on to walls, and the Screw Attack drags foes upwards in a series of spins that doubles as a recovery move. Samus can also use her Bombs to perform Bomb Jumps. - Super Smash Bros. Melee