Mold ID??? what the heck is this thing???? (please help)

I just moved into my mother in-laws house and I noticed whenever she uses the kitchen sink you can hear water in the basement. She said it has been that way for a while. I went into the basement to fix the pipe and I found the entire basement submerged in 2 inches of standing water and a 4' x 8' area covered by a semi-hard sheet of a possible sentient something.

https://drive.google.com/open?id=1M7YgLiprV4IOOn_Wm9-UgfXtSNM2X-XO

Mold, Fungus, Algae, all three??? I've got the leak fixed and I'm sending her to a family members house tomorrow, My immediate plan is to find some way to vent the area and dump a few gallons of bleach down there while the house is empty... BUT is there a point? Mold, Fungus, Algae, all of the above? Do i have to burn the house down?