Chad brought this remarkable thing back from North Sumatra called Bika Ambon; Ambon being an island that's nowhere near Sumatra, and bika apparently being a cake made out of rice flour. What's remarkable about it is its complex structure, which reminds me of the diagrams of hydrophobic and hydrophilic membranes we studied in high school biology class.
Bika Ambon is pleasantly chewy and has the sort of eggy-custardy-coconut flavor that's very popular in Indonesian desserts. The other interesting thing about it is the warning on the box, which informs us (in Indonesian) that after 3 or 4 days Bika Ambon will "experience a process of hardening." We can attest to this, since our small remaining piece now resembles some kind of construction material. The suggested remedy is steam, but I suspect our remedy will be to let it hang around in the fridge for another week and then toss it.