Metal Salvage (Subnautica)

Metal Salvage is a raw material found scattered on the seabed, usually near wrecks. The PDA states it is illegal to salvage larger pieces of Alterra ships.

In the Kelp Forest, it is picked up and gathered by Stalkers.

If the player holds one in his hand near a Stalker, it will pick it up from the player's hand, temporarily taming the Stalker in the process. Alternatively, a Peeper can be fed to a Stalker, resulting in the creature bringing the player pieces of Metal Salvage in return. However, this is a temporary effect, and the Stalker will soon turn back to its aggressive nature.

It appears to be most common in the Crash Zone and Kelp Forest biomes, but the player takes a risk in visiting these biomes early-game.