Three Month Old 12G DX

Ahh, the memories. 3 hard species to care for:

The Tridacna (corcea clam) that you have needs an established tank and typically intense (Metal Halide) lighting. How much light do you have, if it's the stock 48w the DX has I'm sorry, but it should go back before it dies and knocks your tank out of whack. Once it reaches 3 inches it no long solely relies on feeding but also needs light for nutrition

The Flowerpot (goniopora) isn't a particularly hard species to care for but not a whole lot is known about it and typically doesn't last more than a year. Beautiful coral though

The Sun Coral (Tubastraea) is hard to care for because it's non-photosynthetic, meaning you need to feed it everyday or every other which means that there are excess nutrients being added to the tank daily meaning higher phosphates and nitrates. You need a species tank to properly keep them IMO although a lot of people have sucessfully kept them

Just my .02 since I can regretfully say I've owned all three of those species unsuccessfully. I returned the clam and sun coral back to the LFS and I had a small Goni that no longer came out and I got tired of nursing it so I gave it to a friend.

i agree 100% with what Fluid said....give it back to the LFS.....well at least the Clam...unless you do know what you are doing and the hood has Metal Halides in it....