  We analyse fall-apart decays of poliquark (tetra, penta and molecule type)
hadrons within the constituent quark picture. For processes in which a
poliquark hadron goes to final states containing a light pseudoscalar meson the
constraints given by chiral symmetry are implemented. As an application of the
approach developed, fall-apart decays of $a(980)$ and X(3872) are studied,
assuming these mesons are poliquark hadrons. Two extreme options - confined
diquark-diquark states and molecular states - are considered. For $a^0(980)$,
the observed width can be obtained assuming that this meson is a
diquark-diquark composite with a relatively large size of around $1\div 1.5$
fm. The pure $K \bar K $ molecular-type state, however, can be excluded. For
the X(3872), a sufficiently small width can be obtained if it is a dominantly
isospin-0 diquark-diquark composite with a very large size of $\ge 2.5$ fm. The
pure molecular option appears possible if the binding energy is tiny,
$E_b\lesssim 0.2$ MeV, corresponding to a huge size.
