the giant gray thing

Just a guess here, so heed or discard as appropriate:

Did it look a bit like a cross between a dead miniature dolphin and a deformed, grey, shell-less shrimp? (Mine was actually mottled gray and brownish, the pattern and coloring resembling that on the kind of mushroom they put on mushroom pizzas. I still cannot eat mushroom pizza.)

I passed one of the above-described after having the great fortune to be poured full of IV doxycillin (sp?) when hospitalized for a massive bile duct obstruction. I am guessing the IV doxy killed a whole meagerie of flukes -- I saw lung flukes, liver flukes, and the grey, 1.5"-long horror I named "Big Mama," put up in formaldehyde and hid from myself because it was so repellent.

A friend of mine at the CDC i.d.'d it from the photos I sent her as an intestinal fluke. --As had I, though I didn't "lead" her I.D. (I studied foodborne illnesses at the CDC on a fellowship back in 2004. Little did I know I would get to use my knowledge on myself 7 years later. Yuck.)

Immature intestinal flukes are pictured on the CDC parasite image library. Tweet