I dont know if i can consider a easter egg, but i found those ones
(https://steamuserimages-a.akamaihd.net/ugc/1811019408064004535/AC7882BCF3495AF4F7836910F38A9E530C3031BC/?imw=5000&imh=5000&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false)