Lonely orchid without a name

[DTB]

I have recently set up a terrarium and have one plant that I have no identification for. One of your very helpful members suggested it may be a Dendrobium. Ive attached some pic when it flowered to hopefully narrow it down even more.

Details of the plant are:
I have 20 or so of these growing on my balcony.
The young plants grow out of the top of the old ones. When the roots start to grow I simply pluck it off the top and plant it. It grows to about 5-10 cms (2-4 inches I think) in height.
The flowers are tiny, smaller than your little finger nail.

here are some pics, any ideas?

Thanks

[IMG]_MG_9940_zpstmryfdvh by David Burgess, on Flickr[/IMG]

[IMG]_MG_9937_zpsmffktica by David Burgess, on Flickr[/IMG]

[IMG]_MG_9936_zpspw8dtstg (1) by David Burgess, on Flickr[/IMG]

[IMG]image1 by David Burgess, on Flickr[/IMG]

[IMG]image2 by David Burgess, on Flickr[/IMG]

---------- Post added at 06:17 PM ---------- Previous post was at 05:36 PM ----------

Ok, Google is pretty amazing.
Possibly Dendrobium Kingianum????
I do live in Australia so it would make sense and it does grow like crazy.

https://en.wikipedia.org/wiki/Dendrobium_kingianum

https://www.amazon.com/Orchid-Insani...00PC5JJSEAJVN6