Mystery creature spawning at night; what are they babies of?

[DaJMasta]

Background on the tank: The tank was 11 days old at the time I saw the spawning event, and it had been 3 days since I put in the live rock, maricultured in the Gulf.  Lots of live stuff on it, lots yet to discover, but I know I've got two mantis shrimps, and the larger of the two (about 2" long) is probably the largest mobile creature in the tank, though there are wing oysters, sponges, anemones, crabs, etc..  These little creatures hatched after lights out, and there was very little evidence of them the following morning (a new tank is probably an especially bad place for them, whatever they are).

 

Then I took a few in a tiny beaker and put them under a microscope to get a better view:

...they definitely look like baby mantis shrimp to me.  And since I have two of smallish adult sizes which seem to sometimes share burrows, they could be a pair.  That said, from what I know of mantis shrimp lifecycles, the creatures hatched directly from eggs should be nauplii, which don't look like the adults... which means these wouldn't be mantis shrimp?  So what could they be?  Are there mantises that could have a different lifecycle?

Don't have a positive ID on the mantises, either, one is about an inch and a quarter and is dark blue with orange antennae and slight black banding on the segments, the other is reddish tan and about two inches long, and I know both came in on the rock maricultured in the Gulf.

[seabass]

I'm not sure what they are; but that's very cool.

[LazyFish]

They certainly look like some kind of shrimp to me. Very cool.

[jambon]

I had a similar thing happen. I think my culprit was my candycane pistol shrimp.  

Crustaceans carry there eggs under the tail so it is likely they bred or she was bred before you got it.

[jambon]

If any of them made it into the rock work they should thrive . That could be a headache in the future when your fish start to disappear. Maybe look into how long they remain as the plankton stage. They look cool up close.

[aclman88]

Awesome! Curious where you bought your rock from?

[DaJMasta]

The rock was from Salty Bottom Reef Company, shipped via airline freight so it was in transit only about 12 hours.  Hands down the most life and the freshest rock I've used (still haven't seen an ammonia spike since adding it, I don't expect one at this point), but now I do have to trap some mantises 🙂

[Murphs_Reef]

Looks good