Krynoids are bulky, mobile plants covered in tentacles. They have a very undefined anatomy, with no front or back. Though they have a high tolerance to the cold, high temperatures can damage them.
Krynoids can grow incredibly quickly, easily growing larger then a house in a few hours. Though they require animal proteins while they are young, they can survive on normal photosynthesis later in life. They also don't need roots to gather nitrogen and can gather nitrogen directly from the air.
Krynoids start life as small pods, generally only about 20 centimetres in diameter. Possibly due to the Krynoids' home planet being an extremely volatile environment, many of these pods are launched into space (always in pairs). These pods can survive long trips in space, being able to hibernate for thousands of years.
Once the pod reaches a planet and is exposed to both sunlight and more tolerable conditions, it starts to grow. If a creature comes too close to the pod, it opens up and releases a long shoot, which grabs onto the victim. This infects the victim, slowly turning them into a Krynoid. The victim becomes weak and starts developing plant-like characteristics. At this stage, they still have most of their personality, if intelligent, though they crave animal proteins in order to grow. As time passes, they grow larger and begin to lose all vestiges of their original physical form. Their original personality is lost to the Krynoid sentience.
The Krynoid grows quickly, reaching the size of a house within hours. At this stage, Krynoids can control plants and will aggressively kill all creatures. Finally, the Krynoid will germinate, creating more pods to populate the planet.