You got it. Show Hidden Objects in Nav Pane options reveals those objects
I use it for a number of things including objects such as queries that are likely to be temporary or I think can be deleted after further checking
Just to be really confusing system tables can be divided into 3 types
a) those made visible by ticking Show System Objects e.g. MSysObjects
b) others made visible by ALSO ticking Show Hidden Objects e.g. MSysNameMap
c) yet more 'deep hidden' tables NEVER visible in the Nav Pane e.g. those used for MVFs and attachment fields
Most people, probably correctly, will have no interest in system tables...especially those in b) or c).
I've done the research on all 3 types because it interests me ... and also so nobody else needs to!