Step 1: Locate and characterise the densities. Several oval radiopaque shadows sitting in the midline of the pelvis, where the bladder lies, are typical vesical calculi, which are usually round or oval but can be laminated, amorphous or jackstone-shaped.
Step 2: Consider aetiology. Stasis and infection, classically with urease-producing Proteus in a dysfunctional bladder, generate struvite (magnesium ammonium phosphate) and apatite stones. Patients may have no symptoms or complain of blood in urine, suprapubic ache, an interrupted stream, or repeated urinary infections.
Step 3: Exclude the rest. A calcified uterine fibroid shows a coarse popcorn pattern attached to the uterus, not separate oval stones on the pelvic floor. Bladder carcinoma is soft tissue and does not show as plain-film radiopacity. Renal tuberculosis calcifies the kidney (putty kidney/autonephrectomy) in the upper tract, not centrally in the bladder.
Step 4: Supportive imaging shows them as mobile echogenic foci on a full-bladder ultrasound and as filling defects on contrast studies. The diagnosis is bladder stone.\[\boxed{\text{Bladder stone}}\]