Remains of July 4th fireworks on my roof. Can someone ID?

The night of July 4th while sitting in my den, my next door neighbor began setting off fireworks. At one point, I heard a thud on the roof. I forgot about it until this Saturday...when I was on the roof cleaning the gutters. I found what I believe to be the source of the thud. The first and second image is the actual object. It feels a little like brick mortar, but not as heavy. The third picture, I downloaded off of the web. It too shows a similar object. Since this picture is from the UK, I assume that this remnant is from a common type of fireworks.

I haven't touch this stuff since I was a kid. Can someone ID this remnant, and should it have gotten airborne?

Thanks,
David

Can you dump everything on the hood , or better yet , the front seat of your neighbors favorite car

Then when he knocks on your door , you can ask him

I have the same issue where I live - My Siberian Huskies are half way to China by now

Its a simple harmless plug, although they should of been more considerate if nothing burnt your roof your good.

I got a neighbor Im not thrilled of but its not worth making an enemy for life over minor things over.

Move on, good luck.

Fixed it for you.

Some fireworks have a clay plug to separate the "lift" charge from the "burst" charge. Usually they disintegrate when the "burst" happens, but not always. Looks like that might be your mystery "thud".