[JFP in PA]

There is an SAE test method (I'm away from the shop at the moment, so I don't have the test number at hand) that is used to determine the maximum flow rate of a filter that is used by the manufacturer. Some use more pores of a smaller size to keep up the flow rate without having to resort to making the filter larger, which isn't always possible to to fitment limitations.

The "worms" you are referring to are ususally bits of case sealant (a silicone type product) that squeeze out and eventually break loose into the oil. They usually do not cause a problem unless there is so much of them that they block the oil pickup screens, which cuts off the flow. Jake had some pictures of an engine pickup screens that were totally blocked with this stuff because someone had used way too much sealant when working on the engine.