Bezoar (Buffy)

The Bezoar was a huge and ancient monstrosity trapped beneath the foundation of Sunnydale High School. Its eggs were used in a Teen Health class as "babies" to raise for a class assignment. The spawn that hatched made the students (and certain others, including Giles and Joyce Summers) into slaves that attempted to free their parent. However, they were stopped by Buffy, who dove into the Bezoar's pit and killed the creature.