This area introduces ancient Chozo ruins, indicating a past civilization on SR388. The architecture here often hides secrets and requires clever use of your abilities to navigate. You'll also encounter the Gamma Metroid.
The ruins are characterized by intricate passages, often requiring you to switch between Samus's normal form and Morph Ball form to progress. Look for patterns in the architecture that might hint at hidden blocks or passages. The enemies here are often more resilient, so be prepared for tougher fights.