Some Chimera Ants remember parts, or all, of their life before they were eaten by the Queen.
By eating other creatures, a Chimera Ant queen can impart the characteristics of ingested creatures onto the next generation of Chimera Ants it gives birth to.
Chimera ants are shown to have characteristics that are from two, sometimes more (in the case of Rammot, a combination of human, rabbit and shrike) It is shown that not only human past lives can be remembered, because in Chapter 197 of the manga, Leol remembers being a lion.
However, the chimera ants that remember their past life seem to only remember one. Is it only possible for them to remember one? Why would this be? If they can remember more, why is this never shown?