The rattlesnake calathea (Calathea lancifolia) is a tropical evergreen perennial native to the Brazilian rainforest. It's a member of the prayer plant family, Marantaceae, and is known for its long, wavy green leaves with dark green spots that resemble a rattlesnake's skin. The leaves have a rich purple underside and grow more elongated as the plant matures. 
 
The rattlesnake calathea is a pet-friendly plant that's relatively easy to care for. It prefers consistently moist, well-drained soil and medium to bright indirect light, but can tolerate low indirect light. It should be watered every 1-2 weeks, allowing the soil to dry out half way down between waterings. The plant can benefit from extra humidity, and you can cover the pot with a plastic bag to create a greenhouse effect. However, you should open the bag daily for fresh air and check the soil moisture.