GALVESTON, Texas (AP) — Marine archaeologists made a thrilling discovery this week while examining a well-preserved shipwreck deep in the Gulf of Mexico — two other sunken vessels that likely went down with it during an early 19th century storm.

Much isn’t known about the ships, including the flag or flags they sailed under and the year they sank about 170 miles southeast of Galveston. They came to rest 4,363 feet, or nearly three-quarters of a mile, below the surface, making them the deepest Gulf or North American shipwrecks to have been systematically investigated by archaeologists, the researchers said.

“What you’re going to see and hear I hope will blow your mind. Because it has ours,” lead investigator Fritz Hanselmann told reporters at a Thursday news conference in which the team revealed its initial findings.

“We went out with a lot of questions and we returned with even more. The big question we’re all asking is: What is the shipwreck? And the answer is we still don’t know,” said Hanselmann, a researcher from Texas State University in San Marcos’ Meadows Center for Water and the Environment.

During eight days of exploration that ended Wednesday, the scientists used remote-controlled machines to recover more than 60 artifacts from the initial shipwreck site, including musket parts, ceramic cups and dishes, liquor bottles, clothing and even a toothbrush. The artifacts, including china from Britain, ceramics from Mexico and at least one musket from Canada, will help researchers determine the ships’ histories, Hanselmann said.

“Nationalities, cultures, all collide in these shipwrecks. We hope to return in the future next year with more work,” he said.

Although they weren’t allowed to retrieve artifacts from the two new sites under the terms of their agreement to examine the initial one, the researchers took thousands of photos and closely examined the wreckage of all three ships, which came to rest within five miles of one another.

Two of the ships were carrying similar items, and researchers believe they may have been privateers, or armed ships that governments would hire, Hanselmann said. The third vessel was loaded with hides and large bricks of tallow, suggesting that it may have been a prize seized by the privateers.

The artifacts are headed for preservation work at a Texas A&M University research facility.

“For now, there’s lot of conjecture, lots of hypotheses,” said Jim Delgado, the director of the Maritime Heritage Program for the National Oceanic and Atmospheric Administration. “We may have answered some questions, but we have a large number of new questions. But that’s archaeology.”

Delgado said the ships likely went down during the first two decades of the 1800s, which was a time of great upheaval in the Gulf region, and in the New World in general.