Dear Benjamin, It is likely you have collected a shell of the genus Stomatella, family Stomitellidae, superfamily Trochoidea. Many species look remarkably like abalones, and can easily be mistaken for them. Since they are, technically, top shells, they all have a pearly interior, which can cause further confusion. Freak abalones have been known to lack holes, but it's not very likely that's what you have, especially if you received two. Kind Regards, James