Scavengers are considerably smaller than Thargoid Interceptors, more like the size of a skimmer. They hover above the ground and roam at Surface Sites. They're equipped with some sort of corrosion beam on the frontal area to assemble or disassemble the structure.
They're non-hostile until fired upon. Their only apparent weapon is the ability to spray a lightly-damaging corrosive liquid at attackers. Scavengers can be easily destroyed using conventional Scarab weaponry. This indicates that their purpose is not to handle conflicts.
When destroyed they drop the following Materials: Unknown Fragments, Unknown Carapaces, Unknown Energy Cells, Unknown Organic Circuitry, Unknown Technology Components, Unknown Ship Signatures, and Unknown Wake Data.
Scavengers perform some sort of function related to the Surface Sites. They've been observed to nourish or fertilize the alien eggs on the ground.
They appear to repair or construct the Surface Site with their corrosion beam. The green substance on the surface sites might be the bioweapon known as the Mycoid virus which the INRA unleashed on the Thargoids during the INRA-Thargoid war.