Normal and sounds like urates to me, they do that, I see it as you describe more so with my younger rat and pine snakes then with my adults, the grainly yellow crap thing.
>>I've had this wild-caught black rat for 4 days. Twice there has been a spot on the paper towels that I use for substrate. It's a wet spot a little over an inch in diameter with yellow, grainy stuff in the middle. The yellow stuff looks sort of like cornmeal and is smaller in diameter than a dime. Anybody know what this is? This is my first snake, so I'm new to any and all snake excrement. Thanks.
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Roberts Realm Of Reptile Research
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Thanks,
Frank Roberts

I opened my mouth and out flowed a melody black.