what is the object associated with extraNatural ?

[Bric]

The extraNatural property is a boolean, for key signature change, which 
switches off/on the appearance of cancellation naturals.

But what is the name of the actual engraving object for the set of 
naturals that appear? (Such that one may change its visual properties 
(like color, size, and what not))

Just like one can do this:

        \override Staff.KeySignature.color = #red

It seems one should be able to do this:

        \override Staff.extraNaturalObject.color = #red


I've searched the docs to no avail.