The Burrow is a collection of tunnels in a rock face. The tunnels are half exposed, suggesting they may have been created by the local tunneling bioforms. The name of the room also supports this idea. Many red fungal growths are present around the room. Some of the tunnels are sumberged in liquid Fuel Gel, while others are blocked by crystalline formations of the substance. Behind the submerged tunnel a cave full of Fuel Gel can be seen. Samus can remove most of the crystal obstacles with the Morph Ball Bombs, however some of the crystals are grey in colour and can not be destroyed by Samus' weaponry. Instead, they can be destroyed by the ignition of the standard coloured crytals, if nearby.
The centre of the Burrow is home to some odd plants that resemble venus flytraps that seem to possess some levels of sentience. If their leaves are touched by Samus' Morph Ball they will twist and withdraw in defence (although there is a notable delayed reaction).
The bottom right of the burrow is also semi-industrialized, with the tunnels being plated over with metal structures rather than just formed out of the rock face. A pipe to the left of this sector feeds into a part of the rock face containing Fuel Gel. It is likely that the Galactic Federation used the Burrow as a source of Fuel Gel. Crystal growths are present in the tunnels here as well, indicating that these structures were built a long time ago. A small panel covering the right-most vertical tunnel in this area will retract if Samus touches it, causing her to drop below to the Burrow's exit.
- Missile Expansion
- This Expansion is inside the mouth of a Bryyonian Golem embedded in a rock face in an alcove, found in the lower left side of the Burrow. Samus must use the Golem's extended hand and perform a double Bomb Jump to reach the Golem's mouth and collect the Expansion.
- Struggle of Exiles
- "As the followers of the Primal Traditions celebrated their victory, a number of surviving Science Lords gathered in a hidden sanctuary. It was there that our foolishness became obvious, and we regretted ignoring the Chozo's warning. We realized the folly of following the ways of science with blind faith - and the peril of all Bryyo. The contamination left from all the battles was spreading, and would soon scour the remaining fertile lands, leaving naught but ash. If left unaided, Bryyo would lose what few safe lands and water remained. Once more, our great minds turned to a grand task... planetary salvation. As our enemies searched the lands for us, the last Lords of Science, we created our final machines and launched them into the heavens."
- Under normal circumstances, Samus will enter this room for the first time from the upper entrance from Hall of the Golems, but she can do some Sequence Breaking in Hidden Court to access Burrow from the wrong side (only in the original version of the game). Interestingly, if she enters the tunnel from this side, there will be an explosive crystal that can be bombed to open the way to the rest of the room, making further sequence breaking possible.