I would like to see a study done on how fast anaerobic bacteria colonizes in the interior of dead rock and under what conditions it does best in. Would not be to expensive but would take some time.
Another idea would be to see how ceratian corals or algaes do under different photoperiods. Algaes would be the cheapest and fairly easy, just need some tank.
Might also be nice to see if feeding fish foods with higher proteins leads then to digest more protein, or just poop it out.
Another fun one coudl be to see if after a coral bleaches you could introduce other colors of zooanxthele algaes to change the color of the coral (making a green coral blue) and if future growth would keep that color.
HTH