From The TimeSplitters Wiki

A Decortive is an object that is used for, well decortive purposes. Here is a list of stuff the decortive is in Mapmaker. Note Decortives only appear in TS3.

Military: A helmet on an end of a gun standing vertical (note: you can't take the gun)| Lab: (To be added)| Horror: a stuffed bear| Egyptian: a golden bird egyptian god statue| VR: (To be added)|