where are these objects of awareness once one has subtracted 'sensory awareness'?
For the sake of not mixing up the meanings of the ground of awareness
, which is a precondition,
and 'sensory awareness' which is the result of causes,
let's refer to 'sensory awareness' as cognition
which is what is experienced only when
the necessary (component) conditions arise with
the ground of awareness.
Cognition, or to be more precise, what is experienced
occurs when the ground of awareness arises with the interaction of various events,
such as the interaction of:
Water 77 to 78 %
fats 10 to 12 %
Soluble organic substances 2%
Inorganic salts 1%
...which is what makes up a human brain.
In this case, it the interaction of these components is the object of awareness,
which is experienced as cognition.
When they interact in the context of the ground of awareness,
that interaction is experienced
as thoughts, emotions, concepts, and so on.
For example, "anger" itself isn't happening in the brain.
Only the chemical interactions
(which arise, with the ground of awareness, as the experience
only those chemical interactions occur in the brain.
Scientists can even show where certain interactions occur in the brain
which are experienced as different types of thought or emotion.
Of course, many of those same objects interact all the time, such as salt and water.
There is nothing in the human body, in a molecular sense,
that hasn't always been here. Carbon, etc.
But up until that point, nothing we would recognize as cognition is taking place,
because they do not arise in the context of awareness.
The moment those chemical and molecular events occur within the context of awareness,
we experience cognition.
and we even experience a "me" experiencing it,
which, of course, the Buddha explained, was inaccurate.
So, to answer your question exactly,
sometimes salt and water is in the ocean and nobody is noticing.