Is this an egg sac on my glass?

[littlemacros]

Sorry this post is all over the place.

I found this thing on my glass last night and decided to take some pictures today. Any guesses would be great. When I lightly poke it contorts then whatever is inside goes back to a full circle...what could this be?

And is this a hydroid? It looks like a microscopic jellyfish, they chill on my glass but if I remove them they pulsate around like how a jellyfish swims

5 gallon pico
currently have in tank:
-deep sand bed
-about 40-50 dwarf cerith snails
- 1 big turbo snail
- 2 medium nerites
- maybe 10 small periwinkle snails
- 1 ninja star snail
- 2 marginella snails
- 5 micro decorator crabs (maybe half the size of dimes)
- maybe 3 or 4 tiny tiny chitons
- 1 pink isopod the size of a rollie polli that swims around at night
- 4 barred venus clams
- 3 blue leg hermits
- 2 giant 7 inch bristle worms I cant lure into traps( swear they have learned the truth of the stocking and wont go near it) and they are SO big, thick and scary, but I only see them once in a blue moon.



-lots of copepods
- TONS of munnid isopods
-tons of micro feather worms
- 6 micro strawberry anenomes (they light up under blue LEDs)
-yellow rock encrusting sponge(pretty sure)
-lots of different macros

2 more questions also,

1. Is my pink rolli pollie isopod gonna cause problems?

2. One of my tiny strawberry anemones at an entire dwarth cerith snail whole should I be concerned? The shell is maybe 2mm long but its been jutting out of the anenomes side

 

[sfin52]

1st pic Hydroid
3rd ball anemone is my thoughts

 

[littlemacros]

Thank you!

 

[sfin52]

Thank you!

Your welcome

 

[samnaz]

My hidden cup coral (similar to strawberry anemones) has devoured countless dwarf cerith snails, the shell even poked a hole through its side a couple times but it seemed unphased. All you can do at this point is hope it’ll survive.

Do you have a photo of the isopod in question? What in the last 2 photos needs an ID?

 

[TriggerFinger]

The last pic is a marginella snail, they are scavengers that live in the sand. I have them breeding in my tank; super cool!