This does not seem to fit any of the categories offered.
They appear to be dolloids without the tails
Welcome to the Plankton Portal!
As @zsil said, these are #Doliolid (most of them #withouttail). You can find them under 'Round' category (or under 'Head with tail' if they've got a tail). Check out the Field Guide for more image examples to each of the categories 😃
Feel free to ask if anything wasn't clear to you.