Hate to burst your bubble, but starfish reproduce by releasing male and female gametes into the water; temperature, light, and other outside indicators tell them to release their gametes at the same time. These two just happen to be crawling over each other.

Their larvae are free-swimming and NOT radially symmetrical. This introduces a cool theory called paedomorphism, check it out if you can, it’s too much detail for me to type here, but it’s a really cool theory of evolutionary development from echinoderms and up.