Abstract Shells

Following on from the Abstract Flowers tutorial, I decided to take it a step further and do Abstract Shells.  I made the one on the left first.  Did you know that sea urchin skeletons come in an amazing range of colors?  I looked at a lot of shells online to get an idea how to draw them.  Then I found and made shapes.  I went a bit mad with some paint splatter.  As much as I like my shells, I thought this one was a bit subdued, so I made another one with brighter and stronger colors.  I tried to have more beach pebbles in this one.  Although I do like both of them, I prefer the one on the right.  What do you think?