This is a re-entry cone, it’s used when we plan to revisit a site in the future.  The drillers use all sorts of tools to guide them, like hi-def cameras attached to the drillstring.  (More on that later..)  In this clip, the re-entry cone is dropped into the water on a one-way trip to the sea floor.

And in this clip taken by structural geologist Juila Morgan, the welders cut the steel cable to release the cone.