The tip of the chromosome — the telomere — has been extensively studied in organisms ranging from yeast to humans. But proteins that regulate its maintenance and replication have not been identified in another model organism, the nematode wormCaenorhabditis elegans, until now. Mutant worms that cannot replicate their telomeres have been identified, and one of the mutated genes, mrt-2, also monitors damaged DNA, providing a link between telomeres and double-stranded DNA breaks.