Беляев Антон,
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
#square{
background-image: url(https://fastweb.it/area-clienti-aziende/gfx/form/error_icn.png);
width: 68px;
height: 68px;
position: absolute;
}
</style>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script>
$(function() {
var a = 3000,
b = $("#square");
! function c() {
a-- && b.css({
"margin-left": Math.round(541 * Math.random()) + "px",
top: "22px"
}).animate({
top: "578px"
}, 5000, c)
}()
});
</script>
</head>
<body>
<div id = "square"></div>
</body>
</html>