What's an antonym for "protrude"?

Say there’s an embossed star in a wall (a). If the star’s surface is closer to the viewer than the wall’s surface (b), you can say the star is protruding. Similarly, if the star’s surface is farther from the viewer than the wall’s surface (c), you can say the star is ____.

Looking for antonyms of “protrude” hasn’t been much helpful.

Here's a sentence showing how it would be used:

The position of the light source and the shade it casts is what determines in most cases if the star is perceived as protruding or as ______.

The closest I got is "carved in the wall", but that's not quite it. Also, the etymological opposite of protrude seems to be intrude, but I don't think "the star is intruding" makes sense.

I’m looking for a verb, but adjectives or adverbs would be appreciated too, as long as I can rephrase the sentence so it conveys the meaning I’m after.

Solution 1:

Consider recessed:

To create or fashion a recess in (TFD)

A recess is defined:

An indentation or small hollow (TFD)

Solution 2:

You could go with indented.

Indent: make a dent or impression in (something).

Alternatively, you could go with the more technical terms, embossed and debossed

Deboss: stamp (a design) into the surface of an object so that it is indented.

Both definitions from OED