### Identification Commonly known as the Grainy Barrel-bubble, this minute gastropod is a master of subtle elegance. To the naked eye, *Acteocina cerealis* looks like a stray grain of white rice—hence its name—measuring a mere 5 to 8 mm. Under a hand lens, however, its architecture shines. The shell is cylindrical and translucent-white, often possessing a polished, porcelain-like sheen. The defining field mark is its sunken spire: rather than pointing upward, the top of the shell is flat or slightly recessed, featuring a deeply channeled suture. Unlike its larger cousin, *A. culcitella*, which grows twice as large and has a more tapered profile, *A. cerealis* remains stout and perfectly "barrel-shaped."
### Habitat & Range This species is a staple of the Eastern Pacific benthos, ranging from the chilly waters of Alaska down to the sun-drenched shores of Baja California. It is a creature of the soft-bottomed world, favoring the fine, silty sands of the low intertidal zone down to depths of 100 meters. Look for them in protected bays and estuaries where the sediment is stable enough to support a rich community of micro-organisms.
### Behaviour *A. cerealis* is a "headshield slug," a group of snails that have evolved for a life of subterranean stealth. You won’t find them crawling openly on rocks; instead, they use a fleshy, wedge-shaped cephalic shield to plow through the top layer of sand. This shield acts like a biological bulldozer, protecting the snail’s mantle as it hunts. They are primarily nocturnal, moving just beneath the surface and leaving behind tiny, faint trails that are a delight for a sharp-eyed beachcomber to spot at low tide.
### Diet Though tiny, this snail is a specialized predator. It spends its life hunting foraminiferans—single-celled organisms with hard, shell-like tests. Using its keen chemosensory organs, it tracks these "forams" through the sediment, engulfing them whole with a surprisingly muscular pharynx.
### Fascinating Fact Because its prey (foraminiferans) is protected by a hard, calcium-carbonate shell, *A. cerealis* has evolved a miniature "rock crusher." Inside its esophagus sits a specialized gizzard equipped with three powerful, calcified plates. These plates grind together like millstones, shattering the shells of its prey so the snail can digest the soft nutrients inside!