BoingBoing by way of Wired you know that it's going be weird biology.
Nearly all Corbicula clams are clones—physically hermaphroditic but genetically male, just like their forbears. But that's not the fascinating part. Corbicula clams add new genetic material to their portfolio by, essentially, stealing eggs from other clams and dumping the maternal genome after fertilization. Most of the time, all the maternal genes get dumped. But sometimes, a few genes are kept and get incorporated into the all-male Corbicula line.
The original paper is in PNAS this week and is available here: Rare gene capture in predominantly androgenetic species.