What does the symbol of what looks like a screw coming out of a mount mean?

You can research International Control and Display Symbol icons if you don't have the owners manual at the following web address; http://dashboardsymbols.com/the-symbols/ My guess from your description would be Check Gas Cap Indicator Symbol which usually indicates the cap is not tight, or has other issues. You can see this symbol at the following web address. Just copy and paste to your browser's upper address bar, and click the go button if the hyperlink isn't working. http://dashboardsymbols.com/2010/11/check-gas-cap-indicator/