[retister]

I would very much appreciate any help with identifying this creature.
The shell was blue at first, then turned reddish after a while, probably after it dried completely.

I scooped it out of the Ionian sea, near the Corinth canal, if it helps.

 

[Silent Bird]

This is super common in the Adriatic sea, (although I haven't found any in recent years). It's called "spider crab", or maja squinado in Latin.

 

[retister]

Thanks a lot, that appears to be it. For some reason I assumed it was something rare...