Sooo....I made a mistake and it's really biting me in the you-know-what. The 2 smaller rock mounds came out of my DT and are all good.
The branch looking rock USED to be in my DT but I took it out probably a year ago. I thought I had cleaned it out, bleached it, etc but well....apparently I didn't. I am currently fighting a major ugly brown algae everywhere thing. Params are doing fine suprisingly so I'm planning to move a few hermits from the DT into the tank and go lights out.
I've also been using a really fine mesh net to drag the water and pull the crud out. Ugh....stupid mistake!!