An x-ray of an atrial myxoma. Photograph: radiopaedia.com
"Myxoma" - A noncancerous, jelly-like tumour composed of soft mucous material and loose fibrous strands. Myxomas usually occur singly, and may sometimes grow very large. They may develop under the skin, in the abdomen, in the bones or, very rarely, inside the cavities of the heart. In this case, thrombi (blood clots) may form, and the flow of blood through the heart may be obstructed. Myxomas can usually be successfully removed by surgery.
"myxoma". British Medical Association (2007). Illustrated Medical Dictionary. 2nd ed. London: Dorling Kindersley (DK). p387.