show Abstracthide AbstractLimestone outcrops, scattered rocky areas composed of calcium carbonate (CaCO3), are often host to a diverse, specialized, and threatened biomineralizing fauna. However, the lack of genomic resources for biomineralizing limestone-endemic species has hindered our understanding of the genomic mechanisms underlying morphological evolution in these environments. In this study, we present the genome of a limestone specialized land snail that expresses heavily biomineralized shell ornaments: Oreohelix idahoensis. We utilized genomic long and linked reads (PacBio CLR: 324.5 Gb; 10x Genomics: 425.8 Gb) with transcriptomic Iso-Seq reads (PacBio CCS: 52 Gb) to produce a relatively contiguous and complete ~5.4 Gb genome assembly of O. idahoensis, the largest molluscan genome assembly published to date (May/2022).