Fushing problem with Tefal pro express Turbo Steam generator?

I have a Model GV8150, 5 Bar, Turbo 150g steam generator..I flushed the unit as per Manufacturer instructions...loads of dirty brown water came out ...when I removed the flushing tube , a small black plastic thing fell out..it's about 4 cm long , perforated , looks like some kind of filter, about the diameter of a pencil- also looks like on one end , it is some kinda push-fit ...I cant see where it fits back in , nothing there that looks like it should fit into ...what is it? what do I do with it??