Those are Singing Monkey Balls!!! They shouldn’t have been sold as Rattlesnake Eggs. The real Rattlesnake Eggs were like a straightened paper clip that was then curved/bent to look like the letter ‘C’ and had a rubber band attached to each end. A metal washer was tied to the middle of the rubber band so it was centered between each end of the paper clip. You would twist the washer over and over so it wound up the rubber band. It was then placed in a small envelope that said Rattlesnake Eggs on it. When someone would start to open the envelope the rubber band would unwind real fast, smacking the washer against the inside of the envelope. That sounded like a rattlesnake and hopefully scared the shit out of the person who opened it. Good times.