White squiggle on glass

[sherb]

Occasionally (once a month or so) I'll get a white squiggle on my aquarium glass, usually about 6" long. It always happens during the night (after lights off) so I've never seen what leaves it.

My guess is that it's from one of the numerous snails; I've got turbos, trochus, ceriths, and margaritas. But I have a lot of other hitchhikers in my tank from starting with live Florida gulf rock.

Any ideas?

 

[ISpeakForTheSeas]

I'd guess cerith snail eggs from the pattern there.