These were small wrinkled 5 mm wide balls at the end of stems of a casuarina tree. At least one small branch had several of these with holes ( parasitoid ?). Most were dry but a single fresh green gall on the same branch had a knobbly surface. When dissected the gall showed several thick-walled locules.
These look similar to galls seen on C.glauca induced by the gall wasp Selitrichodes. I would greatly appreciate help with identifying the gall inducer and the Casuarina species. Thanks.