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.

Connect Coin is an Ethereum based token that was created by a company in Tanzania called Cryptocurrency International. Their focus is on serving as an alternative payment method for e-commerce. They are also developing crypto debit cards called Connect Cards.

PascalCoin is the first blockchain that can be deleted, and reduces the dependency of the entire blockchain history to verify transactions. It is a Proof-of-Work (PoW) cryptocurrency that places a strong emphasis on achieving the same level of scalability as credit card networks such as VISA. Pascal's architecture is based on an innovative cryptographic structure called the SafeBox. It facilitates faster transactions by storing account balances separately from the blockchain. The SafeBox only uses the last 100 blocks on the chain to update transaction history. This allows the network nodes to synchronize much faster while preserving the security of the blockchain, and reducing the computing resources needed to maintain it.
PascalCoin also enables simplified account naming to make it easier to transfer funds.