Yup, just as ED said. That's a carbon protector, not a block. Those two 7/16 nuts on the left and right are the T&R phone line. The middle one is a ground for the protector. That should be a #14 from it to the electrical ground. Any other wires on that ground binding post- cut them off (unless its another #14 to the other protector, but I don't see that.)
If you are courious unscrew one of the carbons (the 1/2" hex caps above the line binding posts) and see what they look like (don't lose the parts). They will short occasionally and need to be replaced by the TELCO.
Looks like you have two lines there and its pretty messy and old. Really wish you would take my advice and have the TELCO replace those with todays version. Better protection, less problems and easier for you to connect to.
-Hal
