Re: Hitchhiker Crab, Plus Possible Poriferan -- 7/28/08 <Hello again!> Thanks so much Lynn even though you didn't know what he was! <You're very welcome!> I thought I was the only person on the internet who still answers all questions and promptly! It's hard work! <Well, we do our best, and yes, it can indeed be hard work -- but it's well worth it!> I run a huge web site myself mostly on freshwater aquariums and ponds. <Excellent, so you can definitely relate, huh!> People don't realize how much time it eats up to respond to so many questions. I thought my photos were pretty good, in fact better than looking at him in person since he's so tiny! <I'm sorry, they were indeed good photos, especially for a small crab! It's just that when it comes to identifying these critters, and especially crabs, it's all in the details. These include shape/texture/color of the overall carapace, whether it's smooth or 'hairy', the number of spines/shape of the carapace edge, eye placement/color, length of eye-stalks, how many legs, the shape/length/color of legs and claws and whether there are any 'teeth', spines, bumps, etc, on them, the shape of the tips of the claws (are they pointed, blunt, or spatulate), the depth of the body, etc, etc, and that's just the basics. LOL The list of criteria goes on and on! The best way to ID these guys is to have it directly in front of you so that you can pick out all the details.> The little crab is in a 3 gallon exile tank <Good> with the Emerald Mithrax crab the store guy told me would be great (great at picking at my star polyps as it turned out). <Yep, that's annoying for sure!> The crabs seem fine but haven't run in to each other yet. <Very good. I'm so glad to hear that he's got a good home. Many of these neat little creatures end up being disposed of and that's a real shame.> Now, that I know someone may be able to help in my new foray in to saltwater, I have a few other unidentified thingamabobs in my tank. One has appeared out of nowhere and grown really fast in under a week. In fact, I didn't even notice it until about three days ago, and it's doubled in size. <Yowza!> It's attached to the live rock under my favorite hitchhiked feather duster. The base is a little fuzzy. The stalk is pastel yellow, almost like a crayon. It has no real mouth, arms, or legs or anything but it is growing. I will have to get a photo. <Please do, I'd love to see it.> It looks like it's calcareous. Today, the tip changed in appearance to have a rectangular-shaped protrusion. It kind of curves up at the end. I'm guessing it's either a strange yellow algae or perhaps a fungus (are there freshwater funguses?). <Sure, there are marine versions as well. Fungi are everywhere. I'm thinking that what you have though could be a Poriferan/sponge of some sort (would need to see a photo). The neat thing about these guys is the diversity of shape and color that they come in. It's truly amazing. For more information/photos, please see Bob's pages regarding sponges, starting here (3 pages): http://www.wetwebmedia.com/sponges.htm . Be sure to check out the associated links at the top of the link as well!> The little feather duster really doesn't like it since it's in its space! I'm wondering if I should bust it off. <Hmmm, well it depends. If it is indeed threatening something you like, you could attempt to remove the offender (although if it's a sponge, many times they simply grow back). If you do (and in case it's a sponge), I'd remove the rock from the tank first. I'd take it out, scrape away as much of the offender as possible, then scrub the area with a toothbrush, and rinse *well* with tank water (into a bucket or similar). Also, you might want to check your nutrient levels/nitrates. The organism's rapid growth could be an indicator of such. In the meantime, if you can get us a photo, we'll see if we can't narrow down/confirm what you've got there!> Thanks again. <You bet. Take care, -Lynn>

Update Re: Hitchhiker Crab, Plus Possible Poriferan, Macroalgae -- 7/30/08 <Well hello again!> Ok, I threw up some photos quickly since I'm low on time. <Appreciate it!> Photo of the entire 12 gallon nano cube showing where the "thing" is: http://www.fishpondinfo.com/photos/other/other/temp1.jpg <Nice looking system.> Photo of the thing a few days ago when it grew fast and was yellow. My favorite little feather duster is open to the right of it.: http://www.fishpondinfo.com/photos/other/other/temp2.jpg <Neat> Photo from today of it with the feather duster, Zoanthids, xenia, macroalgae, etc. When I came home, the thing had turned green!: http://www.fishpondinfo.com/photos/other/other/temp3.jpg <Ah yes, that helps. It looks like some sort of macroalgae, possibly in the genus Halimeda (a calcareous algae). We should be able to tell when it gets a bit farther along (if it's that or something else). Here are some links re: http://www.wetwebmedia.com/greenalg.htm  http://www.reefkeeping.com/issues/2004-04/nftt/index.php  Good photos here: http://www.reefcorner.com/SpecimenSheets/halimeda.htm  It definitely likes the light. <Yep> There were no sponge matches on the site you gave me but fan sponges seem to come the closest. Is that what it is? <Don't think so.> The feather duster has bent itself off to the right to avoid bumping in to this thing that I swear wasn't there at all a week ago! <Funny how things spring up like that isn't it! It's a matter of conditions becoming favorable for the organism's growth/survival.> I put in about 15 ml.s of RowaPhos weekly in a little mesh bag to keep the phosphate low. I use RO water. It takes over two hours to make 3 gallons once a week. <Yikes. That sounds like an awful long time to make just 3 gal's of RO water (is it RO only or actually RO/DI?). Here are some contributing factors to low production: a connection/plumbing problem, small unit, clogged/exhausted membranes, very cold water, or low water pressure. Just for comparison, I have a Typhoon III (75 GPD) RO/DI unit from AirWaterIce that takes about 45 min's to make 3 gallons. That's with the (tap)water pressure at about 68-70gph. In the winter when the water is in the fifties(F) it takes about an hour instead. I'd go through the above list and see if anything pops.> I don't know how those with large tanks do it; they must run the RO all the time which I'd be afraid to do (leaks, wasting huge amounts of water; we're on a well). <Ah, I see. Have you checked the TDS (total dissolved solids) level of the well water? If it's really high, you may be exhausting/clogging the membranes pretty quickly. That would definitely slow things down.> Here are two other photos if you can confirm what I think they are: Pineapple sponge? http://www.fishpondinfo.com/photos/other/other/squirt.jpg <Ding, ding, ding! You are correct. It's a harmless/beneficial little Syconoid sponge, aka a Pineapple or Q-tip sponge.> Sponge of some sort (the yellow thing at the top of the rock)? http://www.fishpondinfo.com/photos/other/other/sponge.jpg <I can't quite tell, but yes, it could be that or one of several other harmless organisms, like a Bryozoan.> Thanks again! <You're very welcome! Take care, -Lynn>