This object was not made by humans. It is an iron meteorite (Campo del Cielo), which formed ~4.6 billion years ago. There is a small (0.5 inch) ceramic magnet attached. Note: Irregular shape, no symmetry, no sharp edges, no straight lines, no flat parts, some regmaglypts, and a little rust. Photo credit: Randy Korotev
The metal in iron meteorites consists of two alloys that together are commonly called iron-nickel (FeNi) metal. The metal in iron meteorites (also, that in stony irons and pallasites) strongly attracts a cheap ceramic magnet. So (this is simple), if you have found a piece of metal that is not strongly attracted to a magnet, it is not a meteorite.
Humans have been making and losing metal things for thousands of years. Much of that stuff, almost certainly anything manufactured before 1900, is mainly iron. Iron metal, e.g., wrought iron and cast iron, also strongly attracts a cheap magnet.
If it looks like metal and attracts a magnet, then you have to have it analyzed for iron, nickel, manganese, and chromium to determine whether it’s man-made or an iron meteorite. However, it’s often easy to tell that it’s manmade just from the shape. Iron meteorites are rounded but not spherical. There are no straight lines, right angles, or flat parts. I’ve never seen an iron meteorite that was long and thin.
All of the photos on this page were sent to me by people who thought the objects might be meteorites. I suspect that most of these things were found with metal detectors. All this stuff is manmade.
If it has flat sides, right angles, or is circular, then it’s not a meteorite.
The cylindrical shiny things at the bottom may be ingots of some nonferrous metal.
The dendritic things may have been molten metal poured into water or another liquid.
Blebs of metal is a sure sign of manmade metal.
I suspect that these things are all aluminum, which is easy to melt. None is rusty (= not iron) and two are broken (= not iron). They all probably started out as beer or soda cans. Several are flat on the bottom side, implying that they were melted in a container and poured onto a flat surface like concrete. If, like aluminum, it is metallic but does not attract a magnet, then it is not a meteorite.