What Causes Hard, Skinny, And Discolored Stool That Sinks, Floats, And Releases An Oily Substance In The Water?

I had skinny poop but it’s was hard not liquid it also had some that would sink and some would float and it was a darker color like in between black and brown and after a minute of being in the water it was almost like it was a oil coming from it discoloring the water a dark color