Checkered Limpet Shell, Lottia strigatella: (Historically known as Aemaea paradigitalis).
The Checkered Limpet Shell is a smooth surfaced white shell with a raised white cap that has a dark rounded hourglass in the middle and alternating dark and white lines extending into the margin.
The shell surface is smooth with an eroded apex. The internal surface is a glossy bluish white that is colored brown in the central area and white bars around the fringes.
Checkered Limpet Shells reach a maximum size of 1.9 cm x 1.4 cm x 0.7 cm. However, the pictured shell below is significantly larger
In Mexican waters they are found on partially protected sloping surfaces in the mid-intertidal zone all along the west coast of Baja and throughout the lower 80 percent of the Sea of Cortez.
The Checkered Limpet Shell is a medium sized member of the Lottiidae Family, which are the True Limpets known in Mexico as Lapas. The members of the family are characterized by having a horseshoe-shaped muscle scar (the scar left by the margin of the mantle and the foot retractor muscles) and conical shells. The coiling of the shell has been completely lost and internally they have only a single ctedinum (breathing apparatus). They reside primarily on rocks in protected areas in the mid-intertidal zone. They feed on algae which they scrape off the substrate with their radula (tongue).
Note: this shell also appears in the literature as Acmaea strigatella and Collisella strigatella but both the Acmaea and Collisella Genus were consolidated into the Lottia Genus in 2007.