An aneurysm treatment device for in situ treatment of aneurysms comprises a collapsible member having a first shape wherein the first shape is an expanded geometric configuration, and a second shape, wherein the second shape is a collapsed configuration that is loadable into a catheter. The aneurysm treatment device is capable or returning to the first shape in the sac of an aneurysm upon deployment, where it occludes the aneurysm. In another embodiment an occlusion device comprises a flexible, longitudinally extending elastomeric matrix member that assumes a non-linear shape to conformally fill a targeted vascular site.