Complex sentence: A few species of shelled land Pulmonates, such as the edible land snail, "Helix pomatia" can create an epiphragm, which is not an operculum, but in some ways serves in place of one.
Split into simpler sentences: A few species of shelled land pulmonates, such as the edible land snail, "Helix pomatia" can create an epiphragm. This is not an operculum, but in some ways it can serve in place of one.