Norvegicus has brown fur on the back with pale grey fur on its belly. The adults normally weigh 150 - 300g, and may reach up to 500g, and are up to 390mm long. They have relatively small ears - which usually do not cover the eyes when pulled forward.
Water regularly during the growing season to keep the soil slightly moist. Reduce watering in the fall, tapering it off as you move toward winter. During its winter dormancy period, it generally does not need water, but you can water it lightly if the soil is completely dry.
This is a cactus that thrives in desert conditions: bright, direct sunlight year-round will help it thrive. Place it in a south- or west-facing window to receive direct sun.
Feed your rat tail cactus liquid fertilizer diluted to about half strength about once every two weeks during the growing season in spring and summer.
Regular room temperatures are just fine, particularly for the spring, summer, and fall. In winter, it helps to keep the plant in a relatively cool place to encourage a rest period; about 50 degrees Fahrenheit is ideal, but it doesn't have to be that cold. Overall, this is a fairly hardy cactus that can tolerate temperatures as low as 40 degrees and as high as 90 degrees, but it is not frost-hardy, so make sure it never freezes.
It may need a larger pot or basket, depending on whether the plant has fully matured, but it definitely needs new potting soil.
