C. edule or C. glaucum?

[dave r]

Although it does resemble glaucum superficially I would still have my doubts. Glaucum,as mentioned above, is always a lighter, thinner shell and the ribbing does go up to the umbones in glaucum. Glaucum is also a shell of lower salinities preferring more brackish waters than edule, you mentioned your specimen was from the Ebro delta, was it in brackish waters or in the open sea?