Is Sei part of Cosmos?

Could you please clarify for me? Is Sei considered to be a part of the Cosmos ecosystem? I've been trying to understand the interconnections within the cryptocurrency space and this point is causing some confusion. I understand that Cosmos is a network of blockchains designed for scalability and interoperability, but I'm not entirely sure if Sei falls under that umbrella. Could you provide some insight into this matter? It would greatly assist me in my understanding of the larger cryptocurrency landscape. Thank you for your assistance.