3D Master
Rear Admiral
Tricorders or even station sensors can't even discern the difference between a changeling made into an object and the object itself. If a founder turns into a rock the sensors and tricorder will detect a rock. When you start arguing that changelings can't become pure rock you've then got to start asking well how can changelings think when they have no brains
Of course they have brains, it just isn't like any brain we've seen.
or how are they able to change their mass from that of a fully grown humanoid to the size of a drinking glass.
Dump material into subspace, and can undoubtedly also pull material back out of subspace.
Evidence would seem to suggest that when a changeling becomes an object they literally become that object or at least 99.9% of their structure does therefore it's not unreasonable to assume that a changeling can change into rock and crush any nanoprobes within them.
The fact that they can change their mass from that of a Humanoid to a small drinking glass means they can compress and condense themselves very tightly, so it's not ridiculous to believe they can condense themselves into a rock and crush even the tiniest of nanoprobes. At the end of the day nanoprobes are still just mechanical machines.
But again, rock like any material, is mostly EMPTY SPACE, with but the occasional molecule here and there. And if the nanoprobes have already infected some of those things of their bodies that changelings can't change (or they wouldn't be changelings anymore) it no longer matters what they change into, it's over.