red eared sliders eating rocks

Question
I have two red eared sliders and I've noticed lately that they're eating the rocks at the bottom of their tanks. Is this normal?
Any information you can give me would be great.
They seem happy, but they always want to eat. it's been hard to feed them their pellets only every other day. They won't touch apples or romaine, but they LOVE earthworms, guppies and meal worms. (they only get these once a week)

Answer
Turtles often eat small pebbles to help grind food and act as ballast. Eating a small amount of pebbles is not a problem.

Young turtles are almost totally carnivores and rarely eat vegetables. This will slowly change as they goet older and slower.

Once a week is a bit rare to be feeding them- a small daily meal would be healthier in general, throwing in an occasional fasting day and a heavier day once in a while.

A good general reference is found at www.tortoise.org.