Snail with black & white checker design on shell?

[Pezcado]

Looks like you could play checkers on this guys shell. Just noticed him crawling around on rocks, size is about a 1/4". Any idea what kind of snail this is?

 

[leaky]

if this is him then remove it and go here to read more... http://www.reefs.org/hhfaq/pages/main_pages/faq_livestock.htm