It's a net so it catches cans thrown at it drive-by style while the thrower rides his bike and doesnt stop, like a boss.
Also, its a net so it doesnt catch water and fill up.
That could be what I was thinking of... I remember seeing (years ago) a fragment of a documentary where they mentioned space dust and had some microscopic green sponge like ball drifting in some stuff on screen. I thought they grew stuff out of space dust ever since ;(