  In this paper we explore the topological properties of self-replicating,
3-dimensional manifolds, which are modeled by idempotents in the
(2+1)-cobordism category. We give a classification theorem for all such
idempotents. Additionally, we characterize biologically interesting ways in
which self-replicating 3-manifolds can embed in $\mathbb{R}^3$.

Geometric Topology