Weird White Round Thing and Scary Worm, Nudi eggs and Bristleworm
Ok wet web crew, maybe you can help. I have just introduced a lettuce nudibranch into my reef tank when I put it in after quarantine (3 weeks) it sunk to a certain spot and stayed in that spot for a whole day, it didn't scoot around as it had in quarantine. This morning it was happily munching on some algae on the other side of the tank, that was a relief, but where it was there is a perfectly round white slimy raised 2" across patch that looks like rings with a hole in the middle on some live rock in the exact spot he sat for the whole day. 
Unfortunately my attempts to photograph were in vain, 80lbs live rock doesn't leave much room to get a pic. Now I was wondering if it was just some kind of reactionary mucus rings left by the nudibranch, or some kind of fluke or roundworm or parasite that the slug just happened to land on and got trapped stuck whatever.
<Mmm, likely a reproductive event... eggs>
I know that sounds unlikely but the more I learn about marine life I don't rule out much these days. 
And totally unrelated this morning I pulled a 4" worm that was covered in what resembled plated spikes, it was a dark brown green, I saw it and yanked out the dead plate I have for decoration he was crawling on. Then I dropped it into hot fresh water, I know its not good to kill stuff if you can't identify but I didn't want to take a chance it was predatory to fish or inverts, so I caught him while I could. Thanks again for your vast wealth of wisdom you share with us all
Mike Yates
<This last is very likely a species of errantiate polychaete... Bob Fenner> 

Lettuce Nudibranch (Elysia)
Dear WWM:
I was looking over my tank today, when creeping around were 5 baby Nudibranchs. They were about 1/8 inch and were bluish gray. About a three weeks ago I had a lettuce Nudibranch, but it died. These animals lay eggs so it might have been from her. I only had one but they are hermaphrodites.
<self fertilization is uncommon but can occur>
One was eaten my Arrow Crab. Should I remove them?
<they are no harm of course if they are truly lettuce Nudibranchs>
My tank is fallow now because of an ich problem so they might survive.
<do avoid (or at least reduce incidence) of Ich/disease with strict quarantine of all new stock (algae, plants, fishes, corals, etc) and stable temps in display>
The tank is a 29 Gallon FOWLR with mushroom corals. Will they harm the mushrooms.
<again... not if they are Elysia>
Thanks Bob Najdek
<Best regards>

Elysia crispata reproduction - Lettuce Nudibranch 11/21/04
Dear WWM Crew, About a year ago I purchased 3 Elysia crispata sea slugs to help combat the extensive growth of hair algae I had growing in my 150 gallon reef. Recently I have noticed 20 or more of what I am pretty sure are very tiny babies of this species.  (If this is so it doesn't say a lot of good things
about the extent of my algae problem)  
<agreed... the Nudibranchs are merely treating the symptom, and not the problem... which is likely a lack of adequate protein skimming if you are like most folks struggling with the same problem. If you own a good skimmer/design... tune and tweak it to produce near daily coffee-dark skimmate to starve the algae into submission in less than 3 weeks (no kidding). Read through our skimmer archives for perspectives on the most reliable skimmer designs/brands... and perhaps upgrade if yours is not a reliable design. If the skimmer is not the problem, here... then there is some other serious nutrient import/export issue at hand>
Just the other day I was able to witness one of the adult slugs laying the spiral egg strand on the glass close to the top of the water line.  I had seen this type of egg case once before in the aquarium (again close to the top) but wasn't sure what had
laid it.  I have read all the information I can find on this species and it sounds as though the eggs hatch out and have a rudimentary shell in their larval stage which they loose before adulthood.  Is this so for this particular species?  Is it possible that the eggs I have seen have developed
into small adults despite all the hazards that such would encounter in a reef aquarium?  
<this species of Nudibranch commonly reproduces in captivity indeed... do enjoy :)>
I was always under the impression that my pump (if not the
corals) would damage any plankton floating about.  
<not so... impeller shear is grossly overstated/-rated>
As an added note I am lucky to have access to a microscope at my workplace and was able to take a small portion of the egg spiral and view this.  I saw what looked like two dark eye spots(?) in each individual which was curled up and had a multiple of segmented sections spiraling outward to the tail section.  I wish I had a way to send a picture of what I saw in the microscope.  I can send in pictures of the egg strand (as long as it hasn't hatched yet) and the babies if anyone is interested.  The egg strand thus far is 12 days old. Laurie
<fantastic my friend... please do document it and share if you can. Best regards! Anthony>