A 6-year-old boy presented with fatigability, shortness of breath, and bulging neck veins. Echocardiography revealed large vegetations, aortic insufficiency, a dilated left ventricle, and bicuspid aortic valve. There was no history of immunocompromise, fevers, or feline exposures. Blood cultures were negative; antibodies against Bartonella henselae were positive. Gentamicin was administered intravenously. Ross procedure was performed and patient was discharged on antibiotics in 5 days. Native valve was thickened by scar and fibrinous vegetations. Warthin-Starry stain demonstrated coccobacilli. Light and ultrastructural morphology, and monoclonal staining implicated B. henselae. Bacterial membranes contain calcium apatite crystals. Antigenic material was present in bacteria and calcified nodules. This case illustrates calcified protobacteria becoming incorporated into scar tissue during endocarditis.