But you have to understand that this is unusual - I am very interested even in a picture of the arm...
If the adult reproduced, then you have something that must be a simulateous hermaphrodite (unless you have a male and female) that is a brooder (few larval brittlestars survive the pumps, etc...and again you would need a male and female brittlestar). This is not impossible by any means, but I would like to document it if possible...even an arm tip picture. What color is the adult?