Maratua critters ID help

Hi friends,

Need your help to identify the critters in the two attached images.

The mollusc (??) burying itself in the sand is ~2cm; there were many of these spread out around the sandy bottom at the house reef on a night dive.

The tiny orange critters on the sponge are no more than 1mm each; they look like baby shrimp/crabs just emerging out of eggs??

Any help appreciated!

Ajay

The first image is an Echinoderm of some sort, maybe an urchin, the second maybe an isopod.

Hi,
number one is a kind of sea urchin, maybe Maretia planulata.

The second shows Commensial Sponge Isopods Santia Sp.

Regards,
Wolfgang

Thanks Bryce, Wolfgang.

Ajay