Toroidal plasma generated by the security systems of Tourian. Rinka turrets defend the Space Pirate command base against intruders. Normally there are at least a dozen turrets installed in any given room of the base, making it easy to get caught in a cross-fire. Rinka turrets are triggered and fire on unauthorized personnel if Tourian’s security doors have been forcefully opened.
Rinkas can be destroyed in a single shot, but are fired rapidly. They move slowly, making them easy to dodge, unless you are stuck in a narrow passage or fighting other enemies. Thankfully, Rinkas can only be fired one at a time. When destroying Zeebetites or fighting Mother Brain, either dodge them or freeze them with the Ice Beam. Power Bombs are another option.
Rinkas appeared in Metroid: Other M as a cameo. Unfortunately, there was no Mother Brain to fight, too.