ID Help snail/worm and sponge

[T3D]

Hello,

I have a few of these things on the rock. I see them at night. I once saw one on glass that looked like a seal. theres a dark center spot on these white circles. They are very small. maybe less than 1/8 inch. Are these dangerous and should I get rid of them?

Also I have these green sponge type materials Any idea on how to id these as well?

Thanks

 

[T3D]

I meant snail not seal. Couldn't edit post

 

[ReefkeeperZ]

the first is a limpet, pretty cool hiker as long as it's not a keyhole limpet (which it does not appear to be), the sponge is a sponge, species of poriferans are typically difficult to ID without a microscope and more knowledge than I posses but that yellow/green guy is pretty common in tanks and I love the look of them. but simply a beneficial filter feeder.

 

[homer1475]

Don't think its a limpet, possibly a stomatella snail.

Either one is good for your tank.

 

[T3D]

the first is a limpet, pretty cool hiker as long as it's not a keyhole limpet (which it does not appear to be), the sponge is a sponge, species of poriferans are typically difficult to ID without a microscope and more knowledge than I posses but that yellow/green guy is pretty common in tanks and I love the look of them. but simply a beneficial filter feeder.

Thank you!

 

[ReefkeeperZ]

Don't think its a limpet, possibly a stomatella snail.

Either one is good for your tank.

I must respectfully disagree.
stomatella are shaped like a rounded fingernail, limpets are teepee shaped.
Stomatella

Limpet