Seed pods from Queensland

The long ones are from the Poinciana or Flame tree. 

I was particularly struck by these seed pods because they are made of wood - or a very solid substance, very strange because these are only the pods and they don't need to be strong or enduring, do they?

I thought at first that the long ones are from a tamarind tree but on Googling these I discovered tamarind pods are shorter and have fruits, not seeds. The very large seed pods come from the Poinciana tree and it is native of Madagascar but grown  in the southern United States (especially Florida) and Bermuda.

Poinciana. F. Caesalpiniaceae. Originally from Madagascar, these decorative trees (up to 12m) typically have a buttressed trunk and a broad, spreading canopy. Their large, compound green leaves can have up to 2,400 fine leaflets with minute hairs. The tree is deciduous before flowering from November to January (in Australia). The quality of the bloom improves with age and after a long, hot dry spell. The long, spectacular racemes of flowers are bright red and blotched with yellow. After flowering the tree becomes loaded with numerous large (up to half a metre flat pods that hang from the foliage. (101 plants of the wet tropics: Martin Cohen and Julia Cooper)

Poinciana tree

The shorter seed pods, however, are from a native Australian tree. The tree is called Black Bean, or Moreton Bay Chestnut. (It's not a chestnut. The Australians call their trees things like Northern Silky Oak and they are nothing to do with the oak trees we have in Europe. Likewise ash.)
Castanospermum australe. These large, straight-trunked trees (up to 35m) grow in rainforest and adjacent habitats and have grey to brown smooth trunks and glossy, dark green compound leaves that provide a dense canopy. ...The large, woody seed pods are long and rounded, each containing three to five large, rounded chestnut like seeds. (Cohen and Cooper)

Mature black bean tree