Protulophila is a genus of symbiotic or commensal colonial Hydrozoa, known from very small hydroids. These marine hydroids live in the shelly tubes of serpulid tube worms, which are annelids. The genus Protulophila was named by Rovereto in 1901, from fossil material. For many years scientists knew these animals only from fossils, and the genus was thought to have become extinct about four million years ago. However, in 2014, animals of this genus were discovered within National Institute of Water and Atmospheric Research (NIWA) museum material that had been live-collected in New Zealand in 2008. Protulophila can be regarded as a living fossil.