Nightfall Ram
The Nightfall Ram is an EXCLUSIVE pet that is available from the Season 1 Toys DLC Codes. There is a 25% chance of obtaining this pet from a Legendary Tier DLC Code. It looks similar to the Snow Ram pet. It was released in an update on June 24th, 2022.
The latest Pet Simulator X value list for Nightfall Ram can be found below:

Regular
💎 125,000,000,000 (125b)

Golden
💎 Coming Soon!

Rainbow
💎 Coming Soon!

Dark Matter
💎 Not Available