This dataset includes measurements of shell properties (e.g. density, volume, and weight) of the ostracode species Paracyprideis pseudopunctillata (subphylum Crustacea), which inhabits the continental shelves of the Arctic Ocean. Using microfocus X-ray computed tomography (microXCT) scans, we generated detailed morphometric measurements of specimens collected from both surface and down-core sediment samples to assess variations in shell properties over time (1915-2018). For each specimen, we calculated a CT number, an index of relative calcium carbonate density, using the equation established by Kimoto et al., 2023.