An hour in, they start showing up mixed in with the octopuses.
As the flow through the hole in the centre of the room trickles to a stop and the pressure shifts to the railway entrances, blister ghouls begin appearing among the Krakaren Juvenile Clonelings at the chokepoints. Their presence is the visible half of the loop Carl has just described: living monsters die, Ghoul Generators make ghouls, and the ghouls come back at the same doors.
Sore-covered ghouls pressing forward among tentacled clones.
The undead half of the waves attacking station 36.