collectively, "ancestors". In exchange for consultation and guidance from their accumulated wisdom, Malagasy take good care of family members who have gone to the spirit world, providing them with adequate homes (tombs are often better built than houses) and festivals (in which the ancestors are rolled out to participate, and rewrapped in new clothes).
Unfortunately, ancestors are innately conservative and necessarily at least a generation out of touch with events. Perfectly acceptable as guides in a static situation, they are of little use when the problems are overpopulation and environmental demolition.