Words to describe different kinds of visibility

I'm looking for a word to describe something that you can't directly see but you still can see ... . E.g., you can see a muscle if it's big and flexed but you can't see it directly because it is under the skin. You don't see, e.g., its color.

So if someone says the muscle is visible - it's slightly different than if someone says the skin is visible - because you can see the skin color but for the muscle, you can't see its color.

I've checked the Oxford thesaurus for visible and various other words but I didn't find any word that would capture that difference.

Does anyone know if there's a word to describe that?

Example sentence. I need it to describe things so "The muscle is X." where X is that special kind of visibility.

Thank you

Solution 1:

"Discernible"/"discernable" and "apparent" would seem to fit the idea that the presence could be inferred from visual cues. Of the two, discernible/able suggests more effort on the part of the person doing the viewing - "apparent" suggests something more obvious.

"Detectable" might work, but it's a broader term and could refer to other ways of detecting than being specifically based on what was seen.

Solution 2:

How about manifestation (M-W): a perceptible, outward, or visible expression, e.g., external manifestations of gender

Example: The large bulges in his upper arms are manifestations of the underlying muscles.