Full Idea
One could argue that some abstract objects exist in all possible worlds (e.g. natural numbers) and that abstract objects always depend for their existence upon concrete objects, and conclude that some concrete objects exist in all possible worlds.
Gist of Idea
All possible worlds contain abstracta (e.g. numbers), which means they contain concrete objects
Source
E.J. Lowe (The Possibility of Metaphysics [1998], 12.1)
Book Reference
Lowe,E.J.: 'The Possibility of Metaphysics' [OUP 2001], p.250
A Reaction
We're all in the dark on this one, but I quite like this argument. I can't conceive of a reality that lacks natural numbers, and the truths that accompany them, and I personally think that numbers arise from the patterns of physical reality.