What metaphors are used in Reef by Romesh Gunesekera?

Triton uses the driftwood to denote the paraphernalia that littered in the parts of the house that were used by the servants. There were quite a few items, old chairs, broken cupboards, cargo boxes that no one could fathom the purpose of, but yet they lounged there and seemed to gather more space. Triton compares all that junk to driftwood from sea, that has washed up to their house from the city.