based solely on your description and the information in your posting i would guess that this was just an undigested seed. many seeds will pass through the gi tract and emerge like this. i don't think this was a parasite or have anything to do with that caterpillar on the celery. i suspect this may be the list time you see these things unless of course you eat sesame seeds again.
single white 1/4" seed-shape on toilet paper after painful bowel movement what is it? . i recently had a very painful bowel movement. i've struggled with constipation since birth. upon wiping there was a sesame shaped spot on my toilet paper but it was about 1/4" in length. i've been eating sesame stix lately could it just be a bloated seed or could it be a parasite? i crushed it between the toilet paper and it was waxy/gel-like. i've also been eating organic produce lately in which i found a tiny caterpillar on the celery. some grapes had black chunks in them i didnt eat those