Any idea what these are? I'll give you a hint, they are often found under rocks.
They are ant cocoons. When people see ant cocoons, they often mistake them for ant eggs. The eggs are actually very small, shiny and white or light-colored. The cocoons are made of silk spun by the ant larvae themselves before they pupate. Ant cocoons are oval and a light brown or beige color.
Children are always interested to learn that the black dot at the end of each cocoon is called a meconium. The larval ants can not get rid of their body wastes because their digestive systems do not pass all the way through to the outside. When the larva pupates within the cocoon, it is finally able to pass the wastes, which form that black dot.
Check out this previous post for more questions children have about ants.