This is an Ootheca. It's the egg case of an American Cockroach. Detective work brought us to the source of the infestation, an open vent cap in the sewer line that was hidden behind a wall space we found with a fiber optic camera.
A temporary patch until the plumber arrived and some sticky traps solved this long standing problem without any chemicals! That's IPM or Integrated Pest Management.
For more information on getting rid of cockroaches, contact EHS Pest in Norwood.