How close to human are vessels?
This is partially a GM’s call (i.e., some GM’s like to use vessels, especially older ones, that give humans some clue about the weirdness they are facing). Canonically, they have fingerprints, they sweat, they have DNA with the proper number of chromosomes, they’re chemically identical to a normal human, etc. Now, since vessels don’t require food and are immune to disease, a researcher might notice some slight anomolies (this person seems to be in perfect health, but their system is entirely free of any trace of food), but nothing outrageous.
