Quarkcoin is a coin which increases security by using 9 rounds of hashing from 6 different hashing algorithms - blake, bmw, grøstl, JH, keccak, skein. 3 of the hashing rounds apply a random hashing function. This compares with Bitcoin's solitary use of SHA-256 algorithm. There is no pre-mine for this coin. A new block is generated every 30 seconds and 2048 Quark is given out as reward per block at the beginning. This reward halves every 60480 blocks or roughly every 3 weeks. The initial supply of Quark is 247 million and this is expected to be mined in roughly 6 months since launch date. The supply will then continue to increase at an inflationary rate of 0.5% per year. Quarkcoin was launched on 21 July 2013.
Stealthcoin (XST) has been rebranded to Stealth (XST): https://twitter.com/stealthsend/status/993226001101545473 Stealthcoin provides a complete anonymity solution for cryptocurrencies. Stealthcoin has a fair distribution with nearly four hours of low block rewards, a small premine of 1%, and the long-term energy efficiency of proof-of-stake minting.