I remember seeing part of a Creature Feature-type movie on weekend television as a kid. This was probably in the late ‘70s, but the movie was an older black and white film. I don’t remember much about it, and what I do might be distorted or wrong at this point.
Anyway, I think some people found one or more mysterious rock eggs. The eggs might have been baseball or softball sized. The eggs are brought back to a house and are left unattended. The people may have left the eggs in their fireplace. One or more monsters hatch out of the eggs and leave “burned” creature footprints on the carpet. I guess the monsters had extremely hot body temperatures.
I don’t remember much about the monsters, but for some reason I think they might have been reptilian and/or invisible. I assume the monsters attacked various people, but I can’t remember anything else.
Any help figuring out this movie would be much appreciated!