It's been a while i'm trying to help Lernid project (which I really appreciate) to find an icon.
As you might remember I've opened a bug report about this issue, and here, at least, after a month and half of discussion, there is a new icon!

This great icon was made by an active art ubuntu user, who call himself Vish. must say that even I (of course) prefer my suggestion more, Vish did a great work

The icon have been committed to the project and suppose to show in your clients on the next update.

have a nice day,
Dor.