Nice Harpoceras from Ilminster, Somerset, UK. Beacon Limestone Formation (Junction Bed). Approx 100mm diameter.
Difficulty: ★ ★ Moderate. Relatively easy to clean. Engraver or an air pen (air scribe).
Outer whorl damaged and mostly missing. Could remove the last remaining bit and keep the inner, or cut it to a base. Should be quite a nice example when prepped. May not be complete to the centre which is reflected in the price.
Looks like a Freshiella on the back - if it is, this is a rare ammonite from the locality - but it is extremely poorly preserved.