Nature Field Guide
Grinning Tun
- Spanish name
- Cambute de lodo
- Scientific name
- Malea ringens
What Do Pico & Tati Think?
A rounded shell with a tooth-lined opening explains its memorable name.
Species overview
About the Grinning Tun
The grinning tun has a swollen, rounded shell with spiral ribs. Tooth-like ridges line the opening. These are shell structures, not a smiling face, but the comparison makes a fun observation activity.
Explorer activity: Draw the opening from a reference image and count the visible ridges. Give your drawing a caption that explains what the “grin” really is.
Your discovery notes: Record the date, place and habitat, then add a sketch or photograph. If you cannot confirm the species, label it “unidentified shell” and keep your observations.
Identification
Key Features of the Grinning Tun
Rounded, inflated shell.
Ribs run around the shell.
Strong ridges along the opening create a tooth-like appearance.
Habitat & range
Shallow coastal marine waters; a washed-up shell does not reveal its original depth.
Local observations
Recorded for Costa Rica’s Pacific coast; Tamarindo location unverified. This supports regional inclusion, not a confirmed Tamarindo Beach sighting.
When to observe
Tides and conditions affect visibility. Let an adult or local guide choose a safe observation time; this card does not promise a seasonal sighting.
Conservation & care
Observe and photograph shells where they are. Leave living animals, occupied shells and empty shells in place. Do not pry animals from rocks, dig in mangroves or put fingers into shell openings. Explore with an adult or guide, follow site rules and stay clear of surf and slippery rocks.
Observation activity
Draw the opening from a reference image and count the visible ridges. Give your drawing a caption that explains what the “grin” really is.
Explore by location
Central Pacific · Guanacaste · Puntarenas & the Gulf Islands · South Pacific