DeLaine:
Apple snails and mystery snails are usually the same thing. From your description of the eggs, I would guess that they are pomacea bridgesii, a type of apple snail.
To learn more about them, and do a definate identification, go here:
applesnail.netYellowish-brown shells sound like the "wild" version of apple snails (the most common variety), which are often sold at pet stores. Other colors available are golden, ivory, brown/yellow striped (wild type-varies from dark brown to light chestnut/yellow), dark and light purple striped, blue and jade. Tan with orange spots on the "foot" is typical coloring for apple snails. The foot can also be blue or ivory with orange spots.
The female lays eggs in a "cluster" above the water line. The eggs start out off-white, then within a few days turn a peachy color as they harden. A male and female are required to produce eggs, but females can store sperm for months. The eggs should hatch within 4-6 weeks if they are left intact. Before they hatch, they become more translucent. Often, the first clutch layed by a snail will be infertile, it is a "practice" clutch, and won't hatch.
Hope this helps!
Laura