Inclusion Criteria:  Male/Female, 18 - 65 years old No self-reported kidney stones during their lifetime (controls) Ultrasound examination confirming absence of kidney stones (controls) Have had at least 1 incidence of a clinically confirmed calcium-based kidney stone in the last 12 months (stone formers) Ability to collect a clean catch urine sample Prescription and over-the-counter drugs unchanged for ≥30 days Willingness to provide medical information, blood, urine, and fecal samples  Exclusion Criteria:  Current, or within 30 days, use of antibiotics or antifungals Current, or within 30 days, use of vitamin K antagonists Current probiotic use or any use within 14 days of screening sample collection should be recorded A history or currently undergoing immunosuppressive drug therapy, chemotherapy, or radiation therapy 2021-06-29 1.0 Page 4 of 6 Fecal incontinence History of disorder with abnormal calcium regulation such as hyperparathyroidism, active malignancy, or osteoporosis.