Sounds like rat/mouse droppings to me, suppose they could be chipmunks as well, I've never seen chipmunk poop, but rat poop is ovular, grenade-like, about half the size of a Tic-Tac candy for mice, possibly as big as a Tic-Tac for rats.

Squirrels have been getting up on our deck this year, they seem to poop in a swirl, piled up in a coil, which I find incredibly fascinating. I've never actually seen them do it, but they always appear on the railings the same day that digging in our pots occurs.

If it is mouse/rat terds, then my question is, why are they here? and what should I do to get rid of them? I've never seen anything like that here, are they nocternal?

Did some more research, confirmed it was green horned tomato worm terds. Then I looked on all my plants for them, but only found one. good news is that it had already been infested w/ the parasitc wasps so I let it be.
thanks/

this is one of those things you can be super proud about figuring out, but you can't tell any of your non-gardening friends, lest they're bound to think, "you were researching poop on the internet?"

:)