the.com/egg tooth
A baby's tiny demolition tool, built only to escape, then deleted.
single useFalls off days after hatching, never seen again
not a toothIt's a hard calcium bump, not real enamel
widespreadBirds, reptiles, and some amphibians all grow one
the jobCracks shell from inside in a process called pipping
monotreme twistEven egg-laying mammals like platypuses have one