Scribbles in the Sand

Olivella biplicata, the purple olive, ploughs a crazy quilt of trails on intertidal sands. A good low tide will reveal Olivella’s handiwork on most any exposed Pacific beach between southern Alaska and Baja California.

What motivates the shape of the trails?

Have a look at the purple olive, a little intertidal snail, only an inch long.

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Olivella biplicata on the move

The purple olive, Olivella biplicata
Last low tide Olivella left me these and I’m posting them as my response to Numbers.





  1. What a neat display of “writing”! These snails remind me of the “moving rocks” at the Racetrack Playa in Death Valley. And also of the trails left by bark beetles on tree trunks.

      1. I’ve been to the Playa and the rock “trails” there are impressive. And there’s lots of “wood words” on the dead trees in our forest. Now, all I have to do is go see Ms Olive and her sandy missives. 🙂

  2. That’s a lovely post for the ‘Numbers’ challenge. Olivella is quite beautiful, and obviously clever with figures, d’you think there’s any chance she can come up with the lottery numbers?! 🙂

    1. I forgot to thank you for your nice comment on my Numbers post. Now days later, I can tell you your lottery idea has given me a smile or two. Would that we could call upon Olivella for winning numbers.

  3. I grew up on a beach where I saw this all the time and never knew what it was. Hadn’t thought about it in years and of course WAY back then there were no computers, let alone Google to find an explanation for these cool trails! I have so many of these shells in my collection! Now I know! Thank you!

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