Although typically found in fantasy space, there is no reason why one couldn't find terrestrial Chickens of Duplication.
There are those who revere the divine entity called the Chicken of Creation, a deific chicken who birthed the world and all within it. (Some believe there are many such chickens, although whether or not there are many Chickens of Creation or merely one is probably not useful for most people.) Among its many progeny is the Chicken of Duplication, a semi-divine chicken of monstrous size. (As with the Chicken of Creation, it is unclear whether there is one Chicken of Duplication or several.)
The Chicken of Duplication is often found flying through other dimensions or even the void of space. If by some strange circumstance you need stats for one, your system probably has an equivalent of a Tyrannosaurus rex; just add a flight speed and you're basically all the way there. They typically don't bother astral ships or other large objects or creatures; they might approach a vessel and give it a curious peck before moving on. Of course, if the occupants decide the peck is an attack and fight back, they will face the full fury of this semi-divine chicken.
Lone travelers are in more peril, as the Chicken of Duplication is roughly as vicious as a regular chicken.
(For Chicken of Duplication stats in 5th edition-style games, I'd start with a regisaur, change the type to celestial, add a fly speed of 120 ft., and change the tail to some manner of stomp or talon attack, dealing slashing damage instead of bludgeoning.)
If the legends are true and there is only one Chicken of Duplication, killing it doesn't stop it: it is reborn in a few days from one of its own eggs. (And like a terrestrial chicken, it lays eggs periodically without fertilization. These eggs are often in remote places in other dimensions. As such, there might be many, many eggs that have not yet been found, and one cannot truly kill the Chicken of Duplication without finding and smashing every such egg.)
The divine beast is rarely seen, but the eggs are the primary reason why anyone knows or cares about it. (It's possible the "Chicken of Duplication" isn't even a chicken; if someone saw a giant chicken and someone else saw a giant hen's egg, a third scholar could have connected the two.) An Egg of Duplication appears to be a hen's egg that is a little larger than human size, somewhere in the seven-by-five-foot range. It feels like a hen's egg, too, although it is significantly stronger — cracking the shell requires a concerted effort, as the shell is harder than steel. It is vulnerable to acid, however. Destroying or cracking the egg renders it inert and kills whatever is inside. (Although if it has not yet been activated, it might produce a truly prodigious amount of yolk. Scholars and sages no doubt would have plenty of uses for the yolk and shell of such a potent celestial egg...)
However, touching the egg with bare flesh causes a reaction. The creature who first touches the egg is enervated, taking a handful of damage, ability score drain, a level of exhaustion, or some similar mechanic that would easily heal in a day or two. No further touches have any effect on either the egg or the person touching it.
If the creature is too large to be contained by the egg, the egg remains inactivated until a creature of the appropriate size touches it.
After being touched, the egg hatches in 1d6+4 days, producing a nude duplicate of the creature who touched it. The duplicate has the same statistics as the original at the time they touched the egg, and the duplicate likewise has access to all of the target's memories until the moment it touched the egg.
As far as anyone can tell, such duplicates have no sinister agenda. However, apart from being birthed from an egg, they believe they are the original, and so will no doubt be very confused and possibly upset by whatever happens next.
