This icon appears when you add a sitemap abstract. There has to be a link to expose the abstract otherwise Google will consider the text (which would otherwise be unreadable by the viewer) as a black hat trick to get better rankings.
You may however change the icon to a small link here:
Website Controls > Manage Site & SEO Settings > Search Engine Settings > Website Sitemap > Use Sitemap icon or link
Article ID: 119, Created: October 8, 2012 at 7:13 PM, Modified: October 8, 2012 at 7:13 PM