U.S. scientists say they may have evidence of the strangest structures believed to exist in the universe: ancient cosmic strings from the time of the Big Bang.

First predicted by astrophysicists in the 1970s, cosmic strings are believed to be enormous cosmic fault lines that formed billions of years ago just moments after the Big Bang when the universe was still an amorphous mass of hot matter, Inside Science New Service reported.

As different regions of the expanding universe cooled in different ways and at different rates, defects formed between the regions, like cracks in the ice on a frozen pond. These defects, scientists believe, were the cosmic strings.

No one has yet directly observed the strings but researchers say they believe they've found evidence of them hidden in quasars, enormous black holes that shoot out mighty jets of light and radiation, found at the heart of many galaxies.

The cosmic strings expanded as the universe grew, possibly into enormous rings thousands of times larger than our galaxy, scientists say.

"Their magnetic field sort of hitches a ride with the expansion of the universe," said Robert Poltis from the University at Buffalo in N.Y.

Poltis' team analyzed 355 quasars to determine the direction their jets are facing in space and found 183 of them lined up to form two enormous rings that stretch across the sky in a pattern unlikely to have formed by chance. The team members theorize the magnetic fields of two cosmic strings affected the direction the quasars are pointing.

The strings themselves would have long since dissipated by emitting gravitational radiation as they stretched, but the original effect on the alignment of the quasars could have remained.

"The string itself is gone, but you get the magnetic field imprinted in the early universe," Poltis said.