The Boost Ball is an upgrade to Samus Aran's Morph Ball seen throughout the Prime Series. While in Morph Ball mode, pressing and holding the B button charges up a "boost", and letting go of the button allows Samus to speed up for a short period of time. The Boost Ball uses kinetic energy to perform its quick movements. It is essential in collecting Dark Torvus Temple Key 1, defeating the Spider Guardian, and shutting down Quad MBs and Dark Quad MBs. It is also able to interface with Spinners, and in Echoes and Corruption, the upgrade gives Samus the ability to Boost Jump off of one Spider Ball Track to another.