  We show that for any positive integer $n$, there exists a quiver $Q$ with
$O(n^2)$ vertices and $O(n^2)$ edges such that any quiver on $n$ vertices is a
full subquiver of a quiver mutation equivalent to $Q$. We generalize this
statement to skew-symmetrizable matrices and obtain other related results. In
particular, we show that any quiver is a full subquiver of a quiver mutation
equivalent to a quiver of a plabic graph.
