This little icon represents a network, with the square in the middle representing the website and the circles around are the users/students. The icon also has a 'scientific symbol' look about it. I also think it looks like a modern, abstract, technical, jolly roger.
yes, i also like that the little icon looks a bit like a humanoid, or little person-kind-of-thing. and i like the juanty look. i also like the welcoming colors. i do wonder if the green on urthling might be better with a green that was bolder, somehow. not sure if that means going toward forest green, or yellow, or blue-earth. hmmm. i'm not a designer..but i do appreciate your thoughtfulness on this. thanks, jim
also has a little person in green as the i, because when I think of urthling I think of aliens for some reason, so a little green person fits with this, (a little left of centre I know) this icon I believe has a young appeal for the age group you're targeting.