The tradition of including a secret easter egg song in zombies map continues in Mauer Der Toten. A new song called Amoeba by Adolescents can be played if you find three cassette tapes around the map.
Unfortunately, this is not an original Kevin Sherwood song for the map, but it is still better than nothing. This guide shows you the locations of all three cassettes with a video guide for your visual reference.
You can collect these tapes by interacting with them.
The first tape is on top of a headless mannequin inside the Garment Factory.
The second tape is located in the Electronic Store just past the bar on East Berlin Street.
As soon as you enter the store, the tape will be right next to you on the shelf.
The third and final tape is found in the Blasted Suite. It is the building with the sign that reads 'Der Dozent' in pink neon color. The building is next to the trial computer on West Berlin Street.
Use the rope to rappel to the blasted suit. You will find the tape resting next to a flower vase on the cabinet.