|This article is written from the Real Life point of view|
In Return of Samus, Metroid Nest is a brooding and unsettling theme that plays in the upper, laboratory-like section of the area. After Samus Aran rolls past the Metroid Egg and her Metroid Detector increases, a shrill stinger plays and then the theme becomes more tense and is played in a higher key. It continues this way up until the last Metroid larva is killed, essentially serving as the game's battle theme for the larvae. At that point, a low droning begins to play in the last corridor before the Queen Metroid. If Samus escapes the Queen battle, this theme can still be heard playing in the rooms before her chamber.
In Samus Returns, the theme's presence is reduced, and it is slower in tempo than the original version, but still eerie. It begins playing slightly earlier in the large open cavern below the nest, and continues until Samus encounters the first Metroid larva, at which point a remix of the Tourian theme begins to play. The nest theme will still play in the previous rooms on subsequent visits.