How do Metagorgers appear and attack when a red Metagorger token is drawn?

Question

Accepted Answer

Drawing a red Metagorger token places one Metagorger in each Room that already holds a Metagorger and/or a Heavy Object (even one a Character carries), plus one in the Nest if it is explored and not destroyed. A Room gets only one, however many objects it holds, and the token goes back to the bag. These placed Metagorgers never make a Surprise Attack, though they count as the first Carnomorph for the Objective discard. When a Metagorger attacks, it is removed and a Shambler token is added to the bag, even if you already hold a Mutation card.

Nemesis: Lockdown

How do Metagorgers appear and attack when a red Metagorger token is drawn?