What is the difference between a crinoid and a blastoid

[Manticocerasman]

I was wondering if there are ways to make out the difference between an isolatad crinoid and blastoid calix, what are the indicators?

[Tidgy's Dad]

I think the main visible difference is that blastoids have the five food grooves running down the sides of the calyx, creating the 'flower-petal' look, while crinoids have actual arms for catching food.  '

[caldigger]

Its so simple...they're spelled differently!