Which blockchain do PRE Tokens operate on?

Ethereum blockchain (ERC-20 token)

Presearch PRE tokens can be found on the Ethereum blockchain as an ERC-20 token. The token contract can be found here on Etherscan:

https://etherscan.io/token/0xEC213F83defB583af3A000B1c0ada660b1902A0Fetherscan.io

PRE Token Contract update is fully 'baked' and ready for Cosmos!

https://etherscan.io/address/0x0d4206fcfa419b954f0b91db7ca8189f75cad226#codeetherscan.io