I haven't heard of the coin before.

Do you mean the Grin coin listed on CoinMarketCap, this one? > https://coinmarketcap.com/currencies/grin/

Its current price at the time of writing this post is: $0.05422

I see that the coin is already listed on Gate.io. Why not sell it through this CEX? If you don't have an account on this exchange, I can help you trade it if you want.