BlackCoin is a Proof-of-Stake (PoS) cryptocurrency created in 2014. Users are rewarded for staking their coins to secure the network. BlackCoin's staking rewards vary between 1% to 8% per year.

The Amp token is a digital collateral token that is specifically designed to enable the decentralized collateralization of digital asset transactions. It evolved from what was previously known as the Flexacoin network, and is meant to allow the token to better facilitate recent innovations related to borrowing and lending in the DeFi space. The Amp token's supply was created by burning the existing supply of Flexacoins, which were exchanged for the new token at a rate of 1:1. Amp will improve upon Flexacoin’s collateralization features with a new architecture that will allow for the implementation of additional on-chain supply operations and more collateral-related DeFi options.

Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.