Big Energy Ball

From Wikitroid, the Metroid wiki

Essentially the precursor to the Energy Stations of Super Metroid, the Big Energy Ball replenishes Samus' entire energy store upon contact. However, unlike the aforementioned Energy Stations of Super Metroid, these large shimmering energy balls are usually found in remote locations within the regular playing field.

Currently, Metroid II: Return of Samus is the only game to feature this item.