WASHINGTON (NEXSTAR) - "We are not alone in the cosmos," former Defense Department Official Luis Elizondo told a House Committee Wednesday. But what's out there is what lawmakers are trying to figure out.  "Is it ours? Is it someone else's? Or is it otherworldly?" Rep. Andy Ogles (R-Tenn.) asked.  Congress held its second House hearing focused on "unidentified anomalous phenomena" or UAPs. Former NASA, Navy and Defense Officials told lawmakers what they believe the U.S. government is keeping from Congress and the public.  "This UAP issue may be the greatest issue of our time, and it's being hidden from you," Retired Navy Admiral Tim Gallaudet said.  Gallaudet says he's seen firsthand evidence of UAPs, starting in 2015 during a naval exercise that captured video.  He said it shows an object "exhibiting flight and structural characteristics unlike anything in our arsenal." Gallaudet says emails about the incident soon disappeared. Another witness who testified, journalist Michael Shellenberger, says there's evidence of objects emerging from the ocean.  "A different source entirely described this pretty extraordinary footage that exists of an orb coming out of the ocean and being met by another orb," Shellenberger said.  A former Defense Department Official Luis Elizondo says he can't legally talk about a UFO crash retrieval program.  "You know you can't talk about fight club if there's no fight club," Rep. Jared Moskowitz (D-Fla.) said.  "Correct," Elizondo said.  Congresswoman Nancy Mace (R-S.C.) says she's concerned about the government overclassifying information that could be impeding national security or science on the dime of the American people. "Taxpayers deserve to know how much has been spent. They shouldn't be kept in the dark to spare the Pentagon a little bit of embarrassment," Mace said.  Former NASA administrator Michael Gold, who also testified, said the vast majority of the unidentified objects are likely drones or experimental aircraft, but he says some of them are anomalies and that's what needs to be studied.