Metroid DNA

Metroid DNA refers to the DNA strand of Metroids in the advanced stages of their life cycle. Metroid DNA strands are an item in the forthcoming Metroid: Samus Returns. The areas on SR388 are blocked off by a toxic purple liquid. To decrease the levels of the liquid so that Samus can safely access the next area, she must collect DNA from Metroids she kills and channel it into a Chozo seal near the liquid. After killing each Metroid, Samus absorbs the DNA into her Power Suit, and then uploads it into the seal using her Arm Cannon.

In Metroid II: Return of Samus, the next area was blocked off by lava until all Metroids in the current area were killed.

On-screen tutorial
"Metroid DNA data is required to unlock this seal. No Metroid DNA is detected."