Ashwinder eggs are the eggs of the Ashwinder, a magical serpent which is born from the embers of an unattended magical fire.
The Ashwinder eggs are extremely hot and flammable, and, if not frozen in time, will light fire to the surrounding area. They are bright red and, when frozen, very valuable.
Some enlarged Ashwinder eggs played a large part in the ending of the Hogwarts school pantomine tradition. In the play, The Fountain of Fair Fortune, an Ashwinder was supplied by Professor Kettleburn to play the 'blind and bloated' worm. The Ashwinder was enlarged with the use of an Engorgement Charm, however things got out of control and the Ashwinder laid its eggs. These eggs, presumed to be enlarged like the Ashwinder, set fire to the floorboards in the Great Hall and ended the Hogwarts pantomine tradition.