Well, the first picture doesn't show anything too clear to me. However, the second picture does seem to place this mystery attachment at approximately near the spot where it appears the lightning bolt that hit my boat 31 years ago exited through the bottom. Bolt must have come down mast, jumped the gap below cuddy interior decking and burned a half-Dollar-sized mark on the inside of the bottom of the hull. Boat developed a small leak after that, previous owner patched hole. Bolt also traveled down the shrouds and fused all the strands of the cable together as it passed over the spreader tips. Previous owner had to replace standing rigging after the shrouds broke at that fused point. That was how my boat got upgraded to the 1/8" rigging she should have had originally.
That happened in 1985, thankfully.. I've had no repeat strikes since I bought the boat in 1996. Well, except that weird experience a couple of years ago, when I was sailing on a clear day with threat of a T-storm. With the storm still a few miles away, I had a sudden sensation of electrical charge in my left arm as I held the tiller (wasn't touching any large metal objects, rudder is solid fiberglass ,tiller is wood). You can bet that my Dad and I quickly lowered and furled the sails and powered home! It took a few hours for the slight tingling to stop in my arm......