Small, almost nano, and needs a tool to extract it. But being a well prepared geocacher you will already have something suitable on hand! (ie: You will need to bring your own pen...)
No need to crawl around under things, it's easily reached from the path. Satellite access may be compromised by the heavy tree cover so I've included a heavy location hint. It's on a public right-of-way, so stealth is required. Parking is available on Mount Shadforth Road at Waterfall Park. (S34°57.541 E117°21.113)
*It's not on it, it's in it!
This has got to be a local record: Published 08:09 and FTF by Bunyip7 at 08:41! Congrartulations Sal!