The most readily recognisable characteristics of eucalyptus species are the distinctive flowers and fruit capsules or "gumnuts". The woody fruits or capsules are roughly cone-shaped and have valves at the end which open to release the seeds.
Find the right one and retrieve to sign the log. Room for small swaps. The lid should be able to be opened with fingers but if it's too tight, there's a tool included.
Unactivated TB for FTF. Congratulations go to Splad_.