Wormhole geometry from gravitational collapse

We discuss a proposal on how gravitational collapse of a null energy condition violating spherically symmetric fluid distribution can avoid the formation of a zero proper volume singularity and eventually lead to a Lorentzian wormhole geometry. Our idea is illustrated using a time-evolving wormhole spacetime in which we show how a collapsing sphere may never reach a zero proper volume end state. The nature of geodesic congruences in such spacetimes is considered and analyzed. Our construction is inspired from a recently proposed static wormhole geometry, the multiparameter Simpson-Visser line element, which is known to unite wormholes and black holes (regular and singular) in a single framework.