dont know if this applies, but the only ‘shell shapes’ logo i have ever seen was on a custom board that i had made here in the u.s. under the ‘hawiian island creations’ label by lynn shell. i ordered the board out of the outer banks in north carolina. as a reference, go to ‘stanleys surfboard logo library’ on the web and under ‘s’ about 1/3rd down the page you will find 2 examples of the logo on my board to compare with yours.