A handsome puzzle book depicting a dozen eggs, with accordion folds that open to reveal what's inside each (ostrich, crocodile, platypus, corn snake, shark, turtle, etc.) and to show its parent and other stages (like tadpoles) and display similar animals (e.g., all five birds that lay eggs underground). A final page gives actual sizes, from 1/10-inch moth eggs to a 10-inch Triceratops egg. Though preschool use is suggested, the detail makes this even more appropriate for older children. The brief text includes surprising facts—e.g., a crocodile carries her babies in her mouth. Dozens of border illustrations add close-up details of habitats as well as eyes, feet, teeth, etc. Compacted into the folded area, some illustrations are oddly truncated—an adult Triceratops head seems to be growing out of a rocky cliff; others are somewhat misleading—the spiny anteater amid eggshells is cuddling a baby too mature to have just hatched. (A spiny anteater egg hatches to produce a thumbnail-sized embryo that then resides in the mother's pouch for two months.) Still, the delicately detailed art and appealing format make this an attractive additional purchase. (Nonfiction. 5-9)