The images below show banana material; a parasite mimic commonly found in stool specimens. These structures are NOT actually banana seeds as is commonly taught in parasitology texts. Instead, they are polymerized tannins associated with xylem strands. The Cavendish bananas that are most often sold in grocery stores do not actually develop seeds. They are naturally sterile (triploid) and can only be propagated vegetatively. However, each aborted ovum has a vascular network consisting of xylem strands and associated cells containing astringent tannins. Upon ripening, the tannins polymerize into a semi-solid mass called 'tannin bodies' which fill the cells. The tannin bodies sometimes incorporate red-brown pigments from polyphenol oxidase activity (like the browning reaction in cut apples) as the cells age, and can therefore be seen as the red-brown bodies in this case. They are associated with the xylem strand which give them a chain-like appearance.