Alien- Tail Goo

She was about to give the order for the group to move when the Necromorph slapped its tail against the pustules on its back, causing black goo to splatter from the ruptured barnacle-like structures. The monster hissed in fury and spun around, showing its back to its attackers and flinging its tail outward. The tail was covered with the viscous black substance from the pustules, and the violent motion sent the slime flying toward the guards.
It struck their faces, hands, chests, and abdomens, and wherever it touched it sizzled and began eating its way into their flesh. The guards shrieked in agony and stopped firing. They dropped their guns and staggered backward, a couple of them cupping hands over melting eyes. The Necromorph slapped its tail against its back once more, and again it flung the tail outward, splattering even more of the acidic pus onto its screaming victims.

Prototype, Chapter 22