Thanks for the nice comment! ^^
The slime is created when the character moves and is positioned at the characters location. It is a sprite with the same size as the floor tiles (64x64).
The 'Duality' is the irony that you play as a cleaner, but you also make the place dirty with your slime. It's a bit out there but it is what I came up with ¯\_(ツ)_/¯