The tunnels form complex networks that interconnect and lead to burrows.

The tunnel formed a spiral that led up and out.

The tunnel will arc around and eventually form a rectangle.

The 14 tunnels form a vital network and are the product of varied construction methods spanning decades.

A tunnel formed ahead of him, and he walked into it.

It came to Sparrow that the marine tunnel formed a grotesque birth canal.

The tunnels formed a kind of road network through the thicket and the drivers seemed to know the routes well.

A dark tunnel formed on either side of his vision and he realized he was passing out.

The tunnel forms a fourth river crossing of the Shannon.

The tunnels formed within a pahoehoe type lava flow.