Name: Townsend Block Z.O.

Dimensions: 8 3/4 inches long, 4 inches wide, 3 3/4 inches height

Location Found: Mansfield, Ohio

Features: 2 parallel grooves on the bottom face

Weight: 10 lbs

Information: Z.O. Stands for Zanesville, Ohio where the block was made. This version has raised letters. For information on other versions of Townsend Blocks see this B.O.B. post: -> Townsend Z O

Other than the company name, I think the structure of this brick looks just like a typical Hocking Block.

To learn more about T B Townsend the owner and his Zanesville Company, you can read portions of this Google Book.