The D&D Creature Catalogue contained these monsters, and I think they came to light in one of the Monstrous Compendiums later. Huge, winged, iron statues imbued with animation and rudimentary intelligence, they are perfect custodians of all sorts of hidden places and important sites.
And they breath fire, which is awesome...and they can stun you with a hit....which is even...errr.... awesomer....???
Google images only had this...art from the days of awesome art!