Based on geochemical and geophysical models, scientists expected Ganymede's interior to either consist of: a) an undifferentiated mixture of rock and ice or b) a differentiated structure with a large lunar sized 'core' of rock and possibly iron overlain by a deep layer of warm soft ice capped by a thin cold rigid ice crust.
(scientists; expected; Ganymede's interior) (warm soft ice; capped; by a thin cold rigid ice crust)
scientists warm soft ice
expected capped
Ganymede's interior
by a thin cold rigid ice crust