Stovebellies. Out of all of the aliens on this wiki, this must be the best one to get for your birthday.
The Stovebellies are natives of the icy shores of a methane sea on Saturn's moon Titan. They eat ice, and in their bodies, they mix the oxygen from the ice and the methane from the air in order to make fires inside their stomachs to keep themselves warm. They move by shooting flame from jets under their bodies. Fishimanders like to snuggle besides them for warmth - until their host blasts off, sending its guests flying. They both appear in the "What if..." part of National Geographic's Picture Atlas of Our Universe.