Plays an important role in ciliogenesis (PubMed:19656802). Interacts with sas-4; leading to its localization into newly forming centrioles. Colocalizes with sas-4 to centrioles throughout the embryonic cell cycle and in sperm (PubMed:19656802). Localizes at the base of mature cilia(PubMed:19656802). Embryos do not show centriole duplication defects, are viable, and develop into fertile adults, but only 10% of the normal number of ciliated neurons are observed. Belongs to the HYLS1 family.