Could it have been conch or some sort of large bivalve, like a geoduck?
It does look a bit like some of the images of sliced abalone I can find. What’s that like, texture-wise?
(NB: the food I had was served in a thick clear sauce flavoured with ginger and garlic, so it was all quite soft and the flavours were mingled and masked.
Sounds like thinly sliced fish balls to me. Very common in Chinese or Vietnamese noodles.
I was going to suggest sliced abalone too.
Less rubbery/chewy than squid, more so than scallops. The meat is also less “fibrous” (can’t think of a better word) than scallop muscle. It’s kinda like a giant periwinkle or snail, if you’ve ever eaten them.
Abalones are expensive especially large ones. They are also firm to chewy (depending on how they are cooked). I wouldn’t think to find large abalones slices in lower priced noodle dishes so that might be another way to tell.