Res nullius is a term of Roman law meaning "things belonging to no one";[1][2] that is, property not yet the object of rights of any specific subject.
Finding can also be a means of occupatio (i.e. vesting ownership), since a thing completely lost or abandoned is res nullius, and therefore belonged to the first taker.
Likewise in common law systems, abandoned things are generally the property of the owner of the land in which they are found.
Exceptions include treasure trove, for which specific law applies, generally making it Crown property; and some types of shipwreck, such as flotsam, jetsam, lagan and derelict.
The concept was applied even where there were indigenous peoples residing in what Europeans considered newly discovered land, as in Australia.