Name the coin and date of transactions with the greatest decline in percent change in 1 hour.
the greatest decline in percent change in 1 hour refers to max(percent_change_1h)
SELECT T1.name, T2.date FROM coins AS T1 INNER JOIN historical AS T2 ON T1.id = T2.coin_id WHERE T2.percent_change_1h = ( SELECT MIN(percent_change_1h) FROM historical )