Calcium sources beyond cuttlebone?

My cockatiel never touches the cuttlebone I put in the cage. What are other good calcium sources for birds? Especially important since mine just laid an unexpected egg...

My vet in Brampton suggested adding foraging opportunities to at least 3 different spots in the cage and I noticed a change within the first week. Highly recommend.

My vet in Leslieville suggested clicker training for 10-15 minutes a day and I noticed a change within the first week. Highly recommend.

Lol my parrotlet does the exact same thing. I've just accepted that the bird runs the house now. I'm just the food delivery service.