Anyone know what this is? (underwater invertebrate)

[KTinTX]

Spotted this in the VERY shallow water at Maho beach last June. Actual size was probably no more than 1-1/2"-2" long. Appeared to be laying eggs in the sand.


148-IMG_0538 by KTinTX, on Flickr

[Exit Zero]

Could be a Red Backed Cleaning Shrimp, sometimes called Scarlet Lady - tough to tell from that angle.

[KTinTX]

The body shape was more like a crawfish than anything else I can relate it to. I have some other images, some better than others, but unfortunately this is the best one of the entire thing.