How to get ID elements from Nodes. Element.Intersects Solid from Bimorph

Can anyone help me how to identify the ID elements of WC from the solid box created in Dynamo.

I tried to create a Script about identify which toilet pan outlet is clashing with Rib Slabs below. My idea is to create a solid box from the connector of the WC, then draw -1000 below slab, then intersect this element with structural framing taken from structural model. I used a node from Bimorph called " Elements. IntersectSolid". Then the outcome was two nodes: The elements ( This one I can take the element ID) The Intersectwith: is all the solid boxs creared from Dynamo. In this thing, I dont know how to take the elements ID of the WC above. Could you please help?. Thanks