The concrete beneath our childrens 8m long swimming pool

 

               See the white vertical stalactite directly above

Rust stains evident in above and below pics.  Structural Engineer, Richard Bax_ndale, is the chap in the light yellow jumper. 

Stalactites are patently evident in the above and below pics

Alas, the above and below pics taken on 1 Jan evidence that the above stalactite is now longer than two months ago.  There is a circular salt stain located directly below this stalactite due to some of the salty water having dripped from the end of this stalactite