Several fans have requested this creature- the Glaucus Atlanticus, a nudibranch. They feed on the portuguese man-o-war and in doing so borrow both their blue tint and toxicity. They look like flowers, so I drew an arrangement of three. The amount of blue varies by individual but it's always striking.
This is a shallow water illustration, so I suggested sand with the tan. A soft drop shadow also helps them to "float".
The last step is the color. I used the pen tool to draw vector shapes to constrain the blue layers. Each has a dark blue, light blue and white layer. The most challenging part was the white stroke in each petal. I am still getting used to the pressure control my wacom tablet offers. I am happy with the end result. If I sketched all day I could not magine such an incredible creature.