I've had him for four months now and he is approximately 2-years-old. His name is Wizzle. He just recovered from an RI, so I keep very close watch on him now. He's definitely a weirdo. Today I found him eating his gravel, he almost started choking, I had to take tweezers and remove it from his mouth. I feed him twice daily, so I don't know why he would eat it. Needless to say, I'm removing the gravel today. What should I replace it with? Large river rocks? And I know that if he tried to eat gravel today he probably has in the past and most likely will try to again. Please advise...
Also, I have this patch of "Sea Grass" that he absolutely loves. The only thing about it is that he goes underneath the grass and picks it up on his shell to the point where he carries it across the tank. He literally power-lifts it. Is that safe? is that okay for him or should I remover that as well?
Any advice is greatly appreciated!
Below are photos of my setup & him power-lifting the grass patch:

