system
Given the following post, respond as if you're commenting on Reddit:
human
If there's a solid object, where its color is completely outside the visible light spectrum, do we see it transparent like glass, or black? What do we see?

Follow up question:

Let's say there's a hypothetical creature X who is completely unable to see our visible light spectrum (eg. their eyes are only sensitive to ultra-violet, and has no overlapping regions with our visible light spectrum range. Or a severely colorblind bird who's RGB sensitivity is zero, but UV is working. Or a creature who could only see the x-ray).

If an object like in the title above is in their visible range, will they see that object as opaque, while we see the object as transparent?

Sorry if my question seems silly. I was just wondering about that, as different ranges of the electromagnetic spectrum could pass through different types of matter.
gpt
You could see it either way, depending on whether it was opaque or transparent to the visible light spectrum.  

It's "color" refers to the light it reflects back into your eye.  The visible spectrum isn't being reflected in your scenario.  That means it is either being transmitted or absorbed.  If it is being transmitted, the object is transparent.   If it is being absorbed it is opaque.  

As far as your creature:  That will depend on the spectrum he sees.  For instance, if he sees in the x-ray spectrum, than objects through which x-rays pass will be transparent for him.  A lead wall thick enough to block x-rays would be opaque.