This is from Weird NJ:

CALDWELL MYSTERY THREAD

ONE OF NEW JERSEY'S MOST BAFFLING MYSTERIES came in the form of a silver "thread" that was suspended for days over the house of Mr. and Mrs. A.P. Smith of 85 Forest St. in the quiet suburb of Caldwell in Essex County.

The "thread" was first reported on Sunday, Aug. 2, 1970 by neighbors who said it appeared to be hanging from the sky. Neither the police nor local townsfolk who came to see it after being reported in the Caldwell Progress could figure out what it was or where it was coming from.

To some, it appeared to be a giant strand hanging from the clouds. Mrs. Smith thought it might be a direct line from the Martians. Others theorized it was a line dropped from a blimp that was cruising the West Essex skies.

The thread was rigid with about a two-pound strength and appeared to be silver when the sunlight would strike it. It appeared over the houses of Forest and Hillside for a week. The Caldwell police tried to track it down, but lost it in the clouds before finding its source.

Dozens of curiosity seekers converged on the area for the next week. Eventually the thread became loose, then disappeared.

Whatever the material was made of, or came from, was never solved. It was reportedly brought to Dupont for analysis, but the company could not determine its origin.