ID Help: Pyrosomes vs Diamondback Squid eggs?

I ran across an organism very much like this one in Indonesia back before iNaturalist:

Asking locals folks got me the info that it was maybe a pelagic tunicate or pelagic squid eggs. When I saw the observation here, I got excited because I thought the mystery would finally be resolved. But looking thru iNat, I found nearly identical photos ID’d as one or the other.

How do you tell them apart? Is it POSSIBLE to tell them apart without a microscope? Neither my photo nor the ones in iNat seem to have enough resolution to see what the red dots are.

Inquiring minds want to know. I still hope to see another one snorkeling or diving some day.

i don’t know anything, but here’s some stuff that might be helpful:

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Yes, I Googled “pyrosome vs squid eggs” and got lots of hits. There are a lot of pictures/videos and not much actual description of how to differentiate. All I can glean is “pyrosomes are more gelatinous” and “pyrosomes are hollow” without any info on the internal structure of egg cases. I’ve seen photos ID’d as pyrosomes that look remarkably gelatinous, with the red spots more internal, but then others look like the spots are closer to the outside surface like the one I poked in West Papua, Indonesia, which seemed gelatinous enough for me but also pretty squishy.

I’m leaning towards squid because its ends didn’t seem as firm and round as some of the pyrosomes, but maybe I didn’t see the official end. They look like they’d break easily.

It’s too bad the DeLoach video (your link #1) didn’t have embryos in the egg case.

Any other IDs I can overanalyze? :rofl:

the second link i posted above does sort of describe what the author thinks distinguishes squid eggs from pyrosomes:

Transparent, pink dots in long thin swirling lines, fragile in appearance–check check check, and check.

additionally, when i look at pictures of squid eggs online, it looks to me like if you were to invert the thing so that the inside of the tube became the outside, it would look exactly the same. but in a pyrosome, the inside of the tube looks different from the outside of the tube. it looks like each of the individual creatures that comprise the pyrosome are themselves like little tubes, with a distinct mouth and butt, with mouth (i assume) facing the inside of the tube and butt (i assume) facing the outside of the tube.

Yes, that’s what they said in the video and their blog. And I agree that the iNat observation looks like it would be the same the same inside out.

But if you look at the observations “confirmed” as pyrosomes (and pictures all over Google), you see a bunch of pyrosome IDs that, under that definition, are squid eggs. I wonder how we’d find an expert to sort it out.

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