Our dear friend Arla Slaughter (Arla Jessen when she lived on the island) identified the mystery sea creature as a “baby’s ear.”  I noted in the blog “A Walk on the Sandbar at the North End of the Front Beach” that we’d found the baby’s ear and didn’t know what it was.  Arla says, “The living mollusk body completely surrounds its shell 🙂  Here’s a link to photos of just the baby’s ear shell — after the creature has passed away.

We’re still trying to figure out what the creature in the minute shell that looks like a tiny lettered olive is.  See the photos below.  The trail and the shell are from the same creature.  If you know what it is, let me know.