evidence: The unidentified flying object shot down in Canadian airspace on Saturday appeared to be a "small, metallic balloon with a tethered payload below it," according to what sources described as a Pentagon memo sent to lawmakers on Monday and obtained by CNN. [...] The memo said that "recovery/exploitation" efforts were underway to retrieve the object shot down in Canada’s Yukon territory, noting that both US and Canadian officials were attempting to identify debris. Canadian officials are leading that investigation, though the FBI was embedded with them, according to the memo. [...] US Coast Guard ships were deployed to search the site in Lake Huron where the third object was shot down, and the Pentagon memo said no additional information was available about the description of that object.