The X have mutated the Geemer into a near-indestructible creature. The Geemer-X hasn't changed much when it comes to its nature, as they can be seen crawling along at a slow pace. When threatened, the Geemer-X will cover up all of its weak body parts with its extremely durable, retractable shell. The shell is so strong that it can withstand direct shots from Samus's cannon.
Unlike normal Geemers, these are completely resistant to Samus's beam weapons and Missiles. Laying a Power Bomb will take them out, but you can also just avoid them completely if you're running low.
Though they are not a SR388 species, the BSL scientists must have had Geemer specimen on the station before the X outbreak. For what purpose, however, is uncertain. The same can be said with other Zebes creatures such as the Sidehopper and Ripper.
