saddle-shaped
/ˈsadlʃeɪpt/adjective
Resembling a saddle in shape; specifically (a) having or consisting of a rounded arch or depression; (b) having or consisting of a steep-sided arch or depression culminating in a central ridge or apex; (c) Science and Mathematics concave in one plane and convex in another; containing a saddle point.
Origin
Late 18th century. From saddle + shaped.