The rich structure of the Schwarzschild interior metric is discussed. In th
e limit of negative pressure, p(r) < 0, it is a closed Universe filled with
a mixture of gases composed of topological defects such as domain walls an
d strings, For p(r) > 0, it is shown that a model of two fluids circumvents
the problem of causality that arises due to uniform density. (C) 2001 Publ
ished by Elsevier Science B.V.