piRNA+Arroganuants+neurogenisis+sea urchin develop experiment

You could try Morpholinos targeting piRNA and look at the effect of the knockdown on neurogenesis.  Sorry I didn't get this to you sooner, I just found your post. 

Morpholinos and piRNA
Houwing S, Kamminga LM, Berezikov E, Cronembold D, Girard A, van den Elst H, Filippov DV, Blaser H, Raz E, Moens CB, Plasterk RH, Hannon GJ, Draper BW, Ketting RF. A role for Piwi and piRNAs in germ cell maintenance and transposon silencing in Zebrafish. Cell. 2007 Apr 6;129(1):69-82.

Recent paper using Morpholinos in sea urchins
Warner JF, McClay DR. Perturbations to the hedgehog pathway in sea urchin embryos. Methods Mol Biol. 2014;1128:211-21. doi: 10.1007/978-1-62703-974-1_14.