First Bonus Question of the Year

Welcome to our first bonus question for the year my favorite Einsteins!!
Please submit your hypothesis as a comment after this post. 
All correct responses will receive a pass to SIT ANYWHERE AT LUNCH (SAP).

Here we go.

 This is a photo from my summer vacation.  What organism made this "trail" and why?

There were many correct answers this week - yahoo - great job Einsteins!!  This is a picture of a female sea turtle's track.  She laid her eggs early in the morning on July 24, 2011, at Cape San Blas, FL.  Her baby turtles will hatch around mid-October.  Stay tuned for more details.