The Stromini were a reptilian race who used a psychic link to feed off of energy from strong emotions like anticipation and excitement. Contrariwise, emotions like disappointment had a debilitating effect. To maintain and build the energy the Stromini extended the passage of time; an hour could actually have lasted weeks or longer.
In December 2011 a Stromini hid inside a gift for a young boy named Gabriel and feasted on the excitement and anticipation. In the end, crushed by disappointment, the Stromini was taken away by the Eleventh Doctor, Amy Pond and Rory Williams in the TARDIS. (DWA: Wait Until Morning)