Because it is part of the same chemical group as Ca, Sr is mostly commonly found as an element co-mineralized with Ca in CaCO3 or CaPO4 biominerals. For example, corals will precipitate Ca and Sr as carbonates in a ratio proportional to their presence in seawater, but also dependent on ambient temperature, which allows Sr/Ca ratios to serve as a measure of temperature (Smith et al., 1979).

Sr, like Ca, can also form skeletal structures surrounding certain protists. Radiolaria are a phylum of unicellular, predatory protists (Eukarya) characterized by mineralized exoskeletons, and are closely related to Foraminefera. While most Radiolaria use Si as the basis for their exoskeletons, those within the order Acantharea have exoskeletons composed of SrSO4 (Biard, 2022).

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A review of Sr effects in human biology notes that Sr can be incorporated at low levels in bone, and this led to the development of strontium ranelate as a treatment for severe osteoporosis (Pors Nielsen, 2004). While the benefits of Sr in the treatment of osteoporosis and healing of bone fractures is well established, increased risks of heart problems have led to contraindications in some populations (Reginster et al., 2015).