Fun fact: If you ever wonder why so many older projects symbol starts with letter X

So you ever wonder why do completely different coins like ripple (XRP), stellar (XLM), tezos (XTZ), monero (XMR), verge (XVG), nem (XEM) start their symbol with letter X ? And does it have something common with precious metals such as gold (XAU), silver (XAG), palladium (XPD) and platinum (XPT) that also use it?

Of course it does.

I guess (as it usually applies for older chains only), this used to be a thing back in the day, when cryptocurrencies would strive for any way they would look a bit more official to the general public, so they made their symbol by the internetional standards.It actually has something to do with something called "currency code", in this case ISO 4217: https://en.wikipedia.org/wiki/ISO_4217#X_currencies

The first letter of the symbol used is an initial for the nation of the currency. In case of "X" it means it has no national preference and acts as a "supranational" currency.

So if you even wondered, now you don't have to :) Cheers.

EDIT: (thanks to brocko33 from the comments) The ISO code of Bitcoin is actually XBT too, rather than BTC. The commonly used BTC violates ISO convention because the first two letters BT are reserved for the country of Bhutan hence cannot be used.