conjoined twin

The hatchling looks like a pair of conjoined twins, with two independently moving heads poking out of its green shell.

Waldhausen said that when the Lincoln babies had their surgeries, there were fewer than two dozen sets of conjoined twins in the world that had been successfully separated at the abdomen.

As the technology got more precise and less invasive, human-to-human links grew seamless, inspired by ancient and intriguing examples of conjoined twins with shared awareness.