We had a seahorse themed birthday party for my youngest daughter. These were super easy and they ended up looking great. To make these I just bought white chocolate and milk chocolate. We melted them in the microwave, following the directions on the bag.
I poured both colors of chocolate into another bowl and then swirled them a little (don’t stir it too much or else it will just become one color). Then, after swirling, I carefully poured them into the shell molds. For the “sand”, We crushed up some graham crackers, then just placed the shells on top. They ended up looking really realistic, and my 6 year old was thrilled!