Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE captain ( captain_id number, name text, ship_id number, age text, class text, rank text )
TABLE: CREATE TABLE ship ( ship_id number, name text, type text, built_year number, class text, flag text )

### Question ###
Return the average and minimum age of captains in each class.

### Accurate SQL ###

SELECT AVG(age), MIN(age), class FROM captain GROUP BY class