Fossil worm adds head to its spiny appearance
New details about ancient creature give hints to evolution of some animals’ teeth
![Hallucigenia sparsa, illustrated](https://i0.wp.com/www.sciencenews.org/wp-content/uploads/2015/06/ay_fossilworm_main_free.jpg?fit=860%2C460&ssl=1)
OUT OF A DREAM Hallucigenia sparsa (illustrated) finally has a head, thanks to a new analysis of fossils.
Danielle Dufault