This is a very old and decrepit specimen. When fresh the underside is white and bruises red if you scrape it (e.g. with a fingernail) or handle it roughly. Here (http://www.anbg.gov.au/fungi/images-captions/amauroderma-rude-0053.html) you can see some specimens in prime condition. The lowest is one I'd turned over and bruised. This is a polypore and on the underside of the cap are numerous small pores. You may be able to make them out with the naked eye but the low magnification of a magnifying glass helps.