The evolutionary origins of Bilateria remain enigmatic. One of the more enduring proposals highlights similarities between a cnidarian-like planula larva and simple acoel-like flatworms. This idea is based in part on the view of the Xenacoelomorpha as an outgroup to all other bilaterians which are themselves designated the Nephrozoa (protostomes and deuterostomes). Genome data can provide important comparative data and help to understand the evolution and biology of enigmatic species better. Here we assemble and analyse the genome of the simple, marine xenacoelomorph

Insights into early animal evolution form the genome of the xenacoelomorph worm Xenoturbella bocki