I know this may not be the best picture to illustrate my concern but he's been sitting up there with his buddy for awhile so I can't really get a great shot. He's a little young blue mystery snail who I purchased in a group of 4 blues. He's the only one who's shell looks like it's starting to grow out darker? He's not as blue as the others but has got a solid shell, not translucent at all except for the small new band of growth. He seems to be eating his veggies and snello just fine so he's getting plenty of calcium and protein. Any ideas?