I noticed it was possible to interact with "seekers" in Shangri La levels. As far as I know (I haven't completed all Shangri La missions yet), seekers are dead people with which you can interact and learn more about Shangri La's lore.
Is there more than lore to uncover ? Does it reward anything to find them all ? Where are they ? I couldn't find one in the "The Hunt For Rakshasa" mission, for instance.