Objects that allow moving in a fluid box

Hi.
I am using a Cp 2019 templates, and I check that it includes objects that seem to have been created as a fluid box, but they really are not and of course it does not appear in the fluid box inspector. Also, I check that it lets these shapes move freely through the space of a fluid box. This is normally not allowed by Cp, the object usually fills the fluid box on which it depends.
Excuse me but I don't know this variant well.
Thank you