The samples I had taken earlier were on the table. Both contents of the zip-lock bag had vanished, just as I had expected. Separated from his body, his hair and the thread from his tunic had ceased to exist in their pseudo-physical form, and had reverted to being part of his mana. In other words, his body and the clothes he wore were woven from the stuff.
Fate/Requiem, Volume 1, Chapter 1