Is there a name for this?

The tree is muti-trunked, but what was really interesting was this unique looking join, like a bridge which to my untrained eye looks like it coud have originated on either trunk, or even have occured as part of a splitting of one trunk into two. I hugely doubt this is the result of anything arbocultural - the tree, though not in the wild, was not part of a cultivated garden but by the side of an allotment - and it seems like some quirk of nature. Is this feature known of, and does it have a name?

 

Interesting Simon, there is a technique called approach grafting or inarching to join varieties that are difficult to graft using other techniques. This can occur naturally where branches cross over each other either in the same tree or different trees. It's seen in living willow sculptures.

 

Inosculation - Wikipedia