This doesn’t sound like anything dangerous.

A few black specks, or even a small dark piece, in otherwise normal stool is just undigested food. The details you gave actually point away from bleeding:
it was a small amount
the rest of your stool looked normal
it broke apart easily and kind of crumbled

When stool is black from bleeding (melena), it’s:
uniformly black, not spots
tarry, sticky, and smeary, not dry or crumbly

What you described, especially that straight edged piece, lines up with something like vegetable skin.

As for the ER part, doctors there are trained to think worst case until it’s ruled out. If someone says there’s black in my stool, their first instinct is to check for blood. That doesn’t mean they think it is blood, they just don’t want to potentially miss anything. I used to work in the ER, and it was the same approach

In non emergency or online settings, it’s more about patterns. You describe what’s going on, and we compare it to what’s textbook.

So the difference is: the ER leans toward testing to be safe, while outside of that, we can usually sort things out based on how it actually presents.

It could be a few things. I was diagnosed with UC. I take a well know safe oral med. Get a colonoscopy

I've eaten a lot of vegetables and other food in my 66 years and have never seen food come out the other end that is black in color. Just to be safe, I'd ask your doctor to send you for a colonoscopy. That is the only way to be sure what is going on. In my opinion at least. I hope everything turns out fine for you!

Details with me was… my body was forcing me to poo hourly. Which was a result of UC irritations. I take balsalazide disodium. , generic Colazal. It took weeks to eliminate my symptoms. It has worked extremely well for 20+ years. No reoccurrence and colonoscopies been clear since starting the med.

Spotty black stool is possible as well as all black stool. On me when I ate something it agitated a lesion and made it bleed, then it would clot and stop bleeding. On October 4 2004 it opened up and I lost so much blood I got a spinal cord injury at C5 C6 and a paralyzed left diaphragm from blood loss, all diagnosed at Mayo Clinic. If you see black, looks like coffee grounds, I recommend getting it checked. I wouldn't wish what I went thru on anybody.

Any blood in stools needs investigation. It could be anything from internal hemmroids, diverticulitis,colon cancer to nothing but the longer you want ,the worse the outcome. Go to GI md, please.