Graboids

Ewwww, what is it???!!!

Guesses - seaworm, centipede, millipede, etc.
We searched online and found it was a sandworm and we were sure because not much is known about them as they burst and die if they feel threatened.  Well, yes, we were poking it and at one point threw it into the ocean to see if it swam . . . but it had already burst in the gut region and wasn't going to give us any kind of show ;)

Sandworms are the creature that the movie Tremors features - graboids - my boys loved those movies - yeah, there's 4 of them.  So unfortunately I am just as familiar with these movies as Brady & Keaton.  I came across this drawing after we returned from San Juan . . . it is just so funny how related things 'pop up' after being recently exposed to similar experiences.
Keaton drew this in elementary school: