The last Mimzy is a nanobyte robot sent from the future to gather DNA (not said specifically DNA) to replace the humanity lost by the people in the future. Emma and Noah find the Mimzy "package" on the beach. Mimzy the bunny can talk and talks to Emma and tells her what she has to do to save the future. Emma saves the future by crying on the bunny named Mimzy (the last Mimzy!). Noah send the Mimzy bunny back into the future via a wormhole.
The future is saved and the future people call Emma their "mother"."