mongoid/mongoid — comment on commit 9dd24779ee940d487d8ea53a3470594db27c6d5f
File: lib/mongoid/cursor.rb line 51
By durran:

Given the same cursor id on the same node, it would pick up where it left off after the connection is dropped (the driver should ensure this goes to the same node). The cursor cleanup is 10 minutes by default on the server side so if they are not explicitly closed they hang around.