These fragile looking creature inhabitat a planet with lower gravity than earth and thus allowing the animals to develop weirder looking shapes.
They possess a bit of snail like abilities, enabling them to protect both, head and eyes, by withdrawing the head further into the body. While the rest of the body is quite static (except for the red extensions), the head, neck area is enormous extendable. Even the eyes can take on awkward looking sizes.
The creature has a high urge to collect any shiny metal it can find - usually attaching them on the red extensions on the back which are quite sticky and are fast growing, allowing them to wrap items quickly. Sometimes they lose a few of those extensions due to sharp metal parts, but these grow back quite fast.
It also can happen that the creature find too many shiny metal objects, which immobilize them completely and eventually kills them. That usually happened quite rarely, since not that many shiny objects naturally lying around, but ever since the humans settled on this planet, more and more die because an overload of metal.
In order to find those shiny object, the Isarnon have a fantastic eyesight.
When first humans started to settle down on this planet, the unnatural high drive for collecting shiny metal parts of the Isarnon was soon discovered (resulting in the name given to it). This unusual behavior made the local humans form a new kind of tradition and people made a sport out of it to attack it with medieval weapons - which is absolutely not dangerous for the humans, since the Isarnon are quite friendly and calm creatures - the only defense it developed is creating noise with the metal parts it collected over time.
This game, called the "game of metal" by the locals, usually involves one human which tries to kill the Isarnon with metal weapons, before the creature manage to steal those weapons. Modern or other ranged weapons as crossbows for instance were strictly forbidden.
Since the species nearly went extinct because of these unfair games, they eventually got forbidden. Some parts of the planet still execute them regularly though, since the people insist this is an important tradition.