I think it doesn't matter who came up with that idea first, each execution of the idea is original and has nothing to do with others, unless the intention is to mimic someone else.
perhaps you could reduce a bit(and only a bit) the saturation. not that i don't like bright colors(in fact, i like them) but slugs tend to have more soft colors...
Looks a tad like a cubed Shrek lol. Cool. (: