snail or pest eggs?

[Makara23]

I have these white pebbles in groups all of a sudden. My shrimps and fish don't eat them so I removed a bunch after a day, but there are still in plenty of spots that are harder to reach. Should I try to siphon them out before they hatch? I have trochus, astrea, limpets, and various cerith snails in my tank. There's also a giant slug in here somewhere, which I'm hoping it's not eggs from!

 

[ISpeakForTheSeas]

Looks like Cerith eggs to me.

 

[Makara23]

Looks like Cerith eggs to me.

I would have thought ceriths lay smaller eggs and in a more neat pattern.

 

[Makara23]

Nevermind! Other google images show ceriths also lay eggs similar to the ones I posted.

What are the chances these hatch, and how can I induce a successful hatch?

 

[ISpeakForTheSeas]

Nevermind! Other google images show ceriths also lay eggs similar to the ones I posted.

What are the chances these hatch, and how can I induce a successful hatch?

The chances of them hatching are pretty good; the chances of them surviving after hatching are not as good (I'm only aware of one Cerithium sp. that has been reared successfully). In most cases, the snails in our tanks have pelagic larvae (free-swimming larvae) that get removed by filters/skimmer/etc., eaten by fish, starve, etc. Some snails (including some Cerithium spp.), however, have benthic larvae (the young are born as basically mini-adults, crawling on the substrate and likely feeding on similar algal species), and these are much more likely to survive.

If yours are pelagic larvae, you'll need a larval rearing tank (a tank that's safe for pelagic larvae) to try and raise them in. You basically just need a little tank (kreisel tanks are ideal, but regular tanks work too) with a bubbler for aeration/flow and a heater to keep the temp tropical; sometimes a specific light condition (such as 12 hours of intensive lighting, or a cave that allows for basically total darkness) or a specific substrate (such as sand, rock, a specific macroalgae, a substrate that is a specific color, etc.) may be necessary as well (this is more common with inverts). Similarly, pelagic larvae will require a specific feed in specific quantities multiple times a day (typically these feeds are either phytoplankton or things like copepods) - the one Cerithium sp. that I'm aware that has been aquacultured was reared using Oocystis sp. phytoplankton (this is not commonly available, so it is very expensive to buy a culture of, and it may or may not work for a different species).

If yours are pelagic larvae and you want to try raising them, I'd try offering Nannochloropsis sp./Tetraselmis sp., and a diatom phyto like Isochrysis galbana (T-Iso), Chaetoceros sp., or Thalassiosira sp. multiple times a day (at least three times daily would be my suggestion). Some snails have been shown to develop well on diatoms until they are ready to settle, then a bottleneck hits and wipes them out - species like this likely need a diet change prior to settlement (it may be a different kind of phyto, it may be a meaty food, or they may need the macroalgae that the adults of their species feed on, I'm not sure).