Hippocampus is a system that uses transactive search to answer memory queries by reconstructing information stored across a group's memories. It discovered and aggregated information about attendees of two conferences by sending invitations to contributors and iteratively reconstructing the lists over time. An experiment found Hippocampus performed up to 46% better than alternatives like machine learning and crowdsourcing at reconstructing complete attendee lists. However, Hippocampus was much slower, so future work will explore incentives to encourage participation.