Likely a remnant of a Sentreye, Service Access.
A Sentreye is a Luminoth security drone. They appear to be red optical devices embedded into walls. They are, as the name suggests, sentries for the Luminoth. Darkling Sentreyes are called Corrupted Sentreyes. No uncorrupted units are encountered in Metroid Prime 2: Echoes.
Official data
Logbook entry
Corrupted Sentreye
Logbook entry
The Sentreyes were designed by the Luminoth to protect their camps on Dark Aether. The Ing learned how to possess them and turned them against their former masters. Many still remain throughout Dark Aether, now serving the Ing as they served the Luminoth before them. Most weapon types will stun the Sentreyes, charged light energy will destroy them.
Trivia
- Quite obviously, their name is a portmanteau of sentry and eye.
- Oddly, normal Sentreyes are not present in Metroid Prime 2: Echoes. The reason may be that Sentreyes were primarily (if not exclusively) used on Dark Aether to protect Luminoth camp sites. As such, normal Sentreyes cannot be scanned or found anywhere. This could also be why they are referred to as "corrupted" instead of "dark". The Sentreye is one of several creatures in-game that do not have a light variation.